How Workers powers our internal maintenance scheduling pipeline

Cloudflare has data centers in over 330 cities globally, so you might think we could easily disrupt a few at any time without users noticing when we plan data center operations. However, the reality is that disruptive maintenance requires careful planning, and as Cloudflare grew, managing these complexities through manual coordination between our infrastructure and network operations specialists became nearly impossible.

It is no longer feasible for a human to track every overlapping maintenance request or account for every customer-specific routing rule in real time. We reached a point where manual oversight alone couldn't guarantee that a routine hardware update in one part of the world wouldn't inadvertently conflict with a critical path in another.

We realized we needed a centralized, automated "brain" to act as a safeguard — a system that could see the entire state of our network at once. By building this scheduler on Cloudflare Workers, we created a way to programmatically enforce safety constraints, ensuring that no matter how fast we move, we never sacrifice the reliability of the services on which our customers depend.

In this blog post, we’ll explain how we built it, and share the results we’re seeing now.

Code Orange: Fail Small — our resilience plan following recent incidents

On November 18, 2025, Cloudflare’s network experienced significant failures to deliver network traffic for approximately two hours and ten minutes. Nearly three weeks later, on December 5, 2025, our network again failed to serve traffic for 28% of applications behind our network for about 25 minutes.

We published detailed post-mortem blog posts following both incidents, but we know that we have more to do to earn back your trust. Today we are sharing details about the work underway at Cloudflare to prevent outages like these from happening again.

We are calling the plan “Code Orange: Fail Small”, which reflects our goal of making our network more resilient to errors or mistakes that could lead to a major outage. A “Code Orange” means the work on this project is prioritized above all else. For context, we declared a “Code Orange” at Cloudflare once before, following another major incident that required top priority from everyone across the company. We feel the recent events require the same focus.  Code Orange is our way to enable that to happen, allowing teams to work cross-functionally as necessary to get the job done while pausing any other work.

The Code Continue reading

Innovating to address streaming abuse — and our latest transparency report

Cloudflare's latest transparency report — covering the first half of 2025 — is now live. As part of our commitment to transparency, Cloudflare publishes such reports twice a year, describing how we handle legal requests for customer information and reports of abuse of our services. Although we’ve been publishing these reports for over 10 years, we’ve continued to adapt our transparency reporting and our commitments to reflect Cloudflare’s growth and changes as a company. Most recently, we made changes to the format of our reports to make them even more comprehensive and understandable.

In general, we try to provide updates on our approach or the requests that we receive in the transparency report itself. To that end, we have some notable updates for the first half of 2025. But our transparency report can only go so far in explaining the numbers. 

In this blog post, we’ll do a deeper dive on one topic: Cloudflare’s approach to streaming and claims of copyright violations. Given increased access to AI tools and other systems for abuse, bad actors have become increasingly sophisticated in the way they attempt to abuse systems to stream copyrighted content, often incorporating steps to hide their behavior. We’ve Continue reading

Announcing support for GROUP BY, SUM, and other aggregation queries in R2 SQL

When you’re dealing with large amounts of data, it’s helpful to get a quick overview — which is exactly what aggregations provide in SQL. Aggregations, known as “GROUP BY queries”, provide a bird’s eye view, so you can quickly gain insights from vast volumes of data.

That’s why we are excited to announce support for aggregations in R2 SQL, Cloudflare's serverless, distributed, analytics query engine, which is capable of running SQL queries over data stored in R2 Data Catalog. Aggregations will allow users of R2 SQL to spot important trends and changes in the data, generate reports and find anomalies in logs.

This release builds on the already supported filter queries, which are foundational for analytical workloads, and allow users to find needles in haystacks of Apache Parquet files.

In this post, we’ll unpack the utility and quirks of aggregations, and then dive into how we extended R2 SQL to support running such queries over vast amounts of data stored in R2 Data Catalog.

Aggregations, or “GROUP BY queries”, generate a short summary of the underlying data.

A common use case for aggregations is generating reports. Consider a table called “sales”, which contains Continue reading

ChatGPT’s rivals, Kwai’s quiet rise: the top Internet services of 2025

In 2025, the Internet is more central to our lives than ever, and we rely on an array of online services to get things done, connect with others, and enjoy ourselves. Cloudflare’s Top Internet Services of 2025 report explores how the connected world interacted this year, based on Cloudflare’s observations and analysis of DNS trends. 

This report is part of the 2025 Cloudflare Radar Year in Review, focused on shifts in popularity of Internet services. We hope you find the results are a compelling view of trends in nine major categories — who’s moving up, who’s sliding down, and who continues to hold our attention.

These rankings show relative popularity within each category, based on anonymized DNS query data from Cloudflare’s 1.1.1.1 DNS resolver and a machine-learning-assisted ranking method introduced in 2022. A lower rank does not imply lower traffic, only that other services may have grown faster.

• Generative AI ➜

• Social Media ➜

• E-commerce ➜

• Video Streaming ➜

• News ➜

• Messaging ➜

• Metaverse & Gaming ➜

• Financial Services ➜

• Cryptocurrency Services ➜

From the dominance of social media and streaming to the rapid growth of AI chatbots, the data Continue reading

The 2025 Cloudflare Radar Year in Review: The rise of AI, post-quantum, and record-breaking DDoS attacks

The 2025 Cloudflare Radar Year in Review is here: our sixth annual review of the Internet trends and patterns we observed throughout the year, based on Cloudflare’s expansive network view.

Our view is unique, due to Cloudflare’s global network, which has a presence in 330 cities in over 125 countries/regions, handling over 81 million HTTP requests per second on average, with more than 129 million HTTP requests per second at peak on behalf of millions of customer Web properties, in addition to responding to approximately 67 million (authoritative + resolver) DNS queries per second. Cloudflare Radar uses the data generated by these Web and DNS services, combined with other complementary data sets, to provide near-real time insights into traffic, bots, security, connectivity, and DNS patterns and trends that we observe across the Internet. 

Our Radar Year in Review takes that observability and, instead of a real-time view, offers a look back at 2025: incorporating interactive charts, graphs, and maps that allow you to explore and compare selected trends and measurements year-over-year and across geographies, as well as share and embed Year in Review graphs. 

The 2025 Year In Review is organized Continue reading

React2Shell and related RSC vulnerabilities threat brief: early exploitation activity and threat actor techniques

On December 3, 2025, immediately following the public disclosure of the critical, maximum-severity React2Shell vulnerability (CVE-2025-55182), the Cloudforce One Threat Intelligence team began monitoring for early signs of exploitation. Within hours, we observed scanning and active exploitation attempts, including traffic originating from infrastructure associated with Asian-nexus threat groups.

Early activity indicates that threat actors quickly integrated this vulnerability into their scanning and reconnaissance routines. We observed systematic probing of exposed systems, testing for the flaw at scale, and incorporating it into broader sweeps of Internet‑facing assets. The identified behavior reveals the actors relied on a combination of tools, such as standard vulnerability scanners and publicly accessible Internet asset discovery platforms, to find potentially vulnerable React Server Components (RSC) deployments exposed to the Internet.

Patterns in observed threat activity also suggest that the actors focused on identifying specific application metadata — such as icon hashes, SSL certificate details, or geographic region identifiers — to refine their candidate target lists before attempting exploitation. 

In addition to React2Shell, two additional vulnerabilities affecting specific RSC implementations were disclosed: CVE-2025-55183 and CVE-2025-55184. Both vulnerabilities, while distinct from React2Shell, also relate to RSC payload handling and Server Function semantics, and are described in more detail Continue reading

Shifting left at enterprise scale: how we manage Cloudflare with Infrastructure as Code

The Cloudflare platform is a critical system for Cloudflare itself. We are our own Customer Zero – using our products to secure and optimize our own services. 

Within our security division, a dedicated Customer Zero team uses its unique position to provide a constant, high-fidelity feedback loop to product and engineering that drives continuous improvement of our products. And we do this at a global scale — where a single misconfiguration can propagate across our edge in seconds and lead to unintended consequences. If you've ever hesitated before pushing a change to production, sweating because you know one small mistake could lock every employee out of critical application or take down a production service, you know the feeling. The risk of unintended consequences is real, and it keeps us up at night.

This presents an interesting challenge: How do we ensure hundreds of internal production Cloudflare accounts are secured consistently while minimizing human error?

While the Cloudflare dashboard is excellent for observability and analytics, manually clicking through hundreds of accounts to ensure security settings are identical is a recipe for mistakes. To keep our sanity and our security intact, we stopped treating our configurations as manual point-and-click tasks and Continue reading

Python Workers redux: fast cold starts, packages, and a uv-first workflow

^{Note: This post was updated with additional details regarding AWS Lambda.}

Last year we announced basic support for Python Workers, allowing Python developers to ship Python to region: Earth in a single command and take advantage of the Workers platform.

Since then, we’ve been hard at work making the Python experience on Workers feel great. We’ve focused on bringing package support to the platform, a reality that’s now here — with exceptionally fast cold starts and a Python-native developer experience.

This means a change in how packages are incorporated into a Python Worker. Instead of offering a limited set of built-in packages, we now support any package supported by Pyodide, the WebAssembly runtime powering Python Workers. This includes all pure Python packages, as well as many packages that rely on dynamic libraries. We also built tooling around uv to make package installation easy.

We’ve also implemented dedicated memory snapshots to reduce cold start times. These snapshots result in serious speed improvements over other serverless Python vendors. In cold start tests using common packages, Cloudflare Workers start over 2.4x faster than AWS Lambda without SnapStart and 3x faster than Google Cloud Run.

In this blog post, we’ll explain Continue reading

Cloudflare outage on December 5, 2025

^{Note: This post was updated to clarify the relationship of the internal WAF tool with the incident on Dec. 5.}

On December 5, 2025, at 08:47 UTC (all times in this blog are UTC), a portion of Cloudflare’s network began experiencing significant failures. The incident was resolved at 09:12 (~25 minutes total impact), when all services were fully restored.

A subset of customers were impacted, accounting for approximately 28% of all HTTP traffic served by Cloudflare. Several factors needed to combine for an individual customer to be affected as described below.

The issue was not caused, directly or indirectly, by a cyber attack on Cloudflare’s systems or malicious activity of any kind. Instead, it was triggered by changes being made to our body parsing logic while attempting to detect and mitigate an industry-wide vulnerability disclosed this week in React Server Components.

Any outage of our systems is unacceptable, and we know we have let the Internet down again following the incident on November 18. We will be publishing details next week about the work we are doing to stop these types of incidents from occurring.

The graph below shows HTTP 500 errors served by our network during the Continue reading

Cloudflare WAF proactively protects against React vulnerability

Cloudflare has deployed a new protection to address a vulnerability in React Server Components (RSC). All Cloudflare customers are automatically protected, including those on free and paid plans, as long as their React application traffic is proxied through the Cloudflare Web Application Firewall (WAF).

Cloudflare Workers are inherently immune to this exploit. React-based applications and frameworks deployed on Workers are not affected by this vulnerability.

We strongly recommend that customers immediately update their systems to the most recent version of React, despite our WAF being designed to detect and prevent this exploit.

Cloudflare has been alerted by its security partners to a Remote Code Execution (RCE) vulnerability impacting Next.js, React Router, and other React frameworks (security advisory CVE-2025-55182, rated CVSS 10.0). Specifically, React version 19.0, 19.1, and 19.2, and Next.js from version 15 through 16 were found to insecurely deserialize malicious requests, leading to RCE.

In response, Cloudflare has deployed new rules across its network, with the default action set to Block. These new protections are included in both the Cloudflare Free Managed Ruleset (available to all Free customers) and the standard Cloudflare Managed Ruleset (available to all paying Continue reading

Cloudflare’s 2025 Q3 DDoS threat report — including Aisuru, the apex of botnets

Welcome to the 23rd edition of Cloudflare’s Quarterly DDoS Threat Report. This report offers a comprehensive analysis of the evolving threat landscape of Distributed Denial of Service (DDoS) attacks based on data from the Cloudflare network. In this edition, we focus on the third quarter of 2025.

The third quarter of 2025 was overshadowed by the Aisuru botnet with a massive army of an estimated 1–4 million infected hosts globally. Aisuru unleashed hyper-volumetric DDoS attacks routinely exceeding 1 terabit per second (Tbps) and 1 billion packets per second (Bpps). The number of these attacks surged 54% quarter-over-quarter (QoQ), averaging 14 hyper-volumetric attacks daily. The scale was unprecedented, with attacks peaking at 29.7 Tbps and 14.1 Bpps.

Other than Aisuru, additional key insights in this report include:

1. DDoS attack traffic against AI companies surged by as much as 347% MoM in September 2025, as public concern and regulatory review of AI increases. 

2. Escalating EU-China trade tensions over rare earth minerals and EV tariffs coincide with a significant increase in DDoS attacks against the Mining, Minerals & Metals industry as well as the Automotive industry in 2025 Q3.

3. Overall, in the third quarter of 2025, Cloudflare’s autonomous Continue reading

Why Replicate is joining Cloudflare

We're happy to announce that as of today Replicate is officially part of Cloudflare.

When we started Replicate in 2019, OpenAI had just open sourced GPT-2, and few people outside of the machine learning community paid much attention to AI. But for those of us in the field, it felt like something big was about to happen. Remarkable models were being created in academic labs, but you needed a metaphorical lab coat to be able to run them.

We made it our mission to get research models out of the lab into the hands of developers. We wanted programmers to creatively bend and twist these models into products that the researchers would never have thought of.

We approached this as a tooling problem. Just like tools like Heroku made it possible to run websites without managing web servers, we wanted to build tools for running models without having to understand backpropagation or deal with CUDA errors.

The first tool we built was Cog: a standard packaging format for machine learning models. Then we built Replicate as the platform to run Cog models as API endpoints in the cloud. We abstracted away both the low-level machine learning, and the complicated Continue reading

Partnering with Black Forest Labs to bring FLUX.2 [dev] to Workers AI

In recent months, we’ve seen a leap forward for closed-source image generation models with the rise of Google’s Nano Banana and OpenAI image generation models. Today, we’re happy to share that a new open-weight contender is back with the launch of Black Forest Lab’s FLUX.2 [dev] and available to run on Cloudflare’s inference platform, Workers AI. You can read more about this new model in detail on BFL’s blog post about their new model launch here.

We have been huge fans of Black Forest Lab’s FLUX image models since their earliest versions. Our hosted version of FLUX.1 [schnell] is one of the most popular models in our catalog for its photorealistic outputs and high-fidelity generations. When the time came to host the licensed version of their new model, we jumped at the opportunity. The FLUX.2 model takes all the best features of FLUX.1 and amps it up, generating even more realistic, grounded images with added customization support like JSON prompting.

Our Workers AI hosted version of FLUX.2 has some specific patterns, like using multipart form data to support input images (up to 4 512x512 images), and output images up to 4 megapixels. The multipart form Continue reading

Get better visibility for the WAF with payload logging

As the surface area for attacks on the web increases, Cloudflare’s Web Application Firewall (WAF)  provides a myriad of solutions to mitigate these attacks. This is great for our customers, but the cardinality in the workloads of the millions of requests we service means that generating false positives is inevitable. This means that the default configuration we have for our customers has to be fine-tuned. 

Fine-tuning isn’t an opaque process: customers have to get some data points and then decide what works for them. This post explains the technologies we offer to enable customers to see why the WAF takes certain actions — and the improvements that have been made to reduce noise and increase signal.

Cloudflare’s WAF protects origin servers from different kinds of layer 7 attacks, which are attacks that target the application layer. Protection is provided with various tools like:

• Managed rules, which security analysts at Cloudflare write to address common vulnerabilities and exposures (CVE), OWASP security risks, and vulnerabilities like Log4Shell.

• Custom rules, where customers can write rules with the expressive Rules language.

• Rate limiting rules, malicious uploads detection Continue reading

Cloudflare outage on November 18, 2025

On 18 November 2025 at 11:20 UTC (all times in this blog are UTC), Cloudflare's network began experiencing significant failures to deliver core network traffic. This showed up to Internet users trying to access our customers' sites as an error page indicating a failure within Cloudflare's network.

The issue was not caused, directly or indirectly, by a cyber attack or malicious activity of any kind. Instead, it was triggered by a change to one of our database systems' permissions which caused the database to output multiple entries into a “feature file” used by our Bot Management system. That feature file, in turn, doubled in size. The larger-than-expected feature file was then propagated to all the machines that make up our network.

The software running on these machines to route traffic across our network reads this feature file to keep our Bot Management system up to date with ever changing threats. The software had a limit on the size of the feature file that was below its doubled size. That caused the software to fail.

After we initially wrongly suspected the symptoms we were seeing were caused by a hyper-scale DDoS attack, we correctly identified the core issue and were able Continue reading

Replicate is joining Cloudflare

We have some big news to share today: Replicate, the leading platform for running AI models, is joining Cloudflare.

We first started talking to Replicate because we shared a lot in common beyond just a passion for bright color palettes. Our mission for Cloudflare’s Workers developer platform has been to make building and deploying full-stack applications as easy as possible. Meanwhile, Replicate has been on a similar mission to make deploying AI models as easy as writing a single line of code. And we realized we could build something even better together by integrating the Replicate platform into Cloudflare directly.

We are excited to share this news and even more excited for what it will mean for customers. Bringing Replicate’s tools into Cloudflare will continue to make our Developer Platform the best place on the Internet to build and deploy any AI or agentic workflow.

Before we spend more time talking about the future of AI, we want to answer the questions that are top of mind for Replicate and Cloudflare users. In short: 

For existing Replicate users: Your APIs and workflows will continue to work without interruption. You will soon benefit from the Continue reading

Finding the grain of sand in a heap of Salt

How do you find the root cause of a configuration management failure when you have a peak of hundreds of changes in 15 minutes on thousands of servers?

That was the challenge we faced as we built the infrastructure to reduce release delays due to failures of Salt, a configuration management tool. (We eventually reduced such failures on the edge by over 5%, as we’ll explain below.) We’ll explore the fundamentals of Salt, and how it is used at Cloudflare. We then describe the common failure modes and how they delay our ability to release valuable changes to serve our customers.

By first solving an architectural problem, we provided the foundation for self-service mechanisms to find the root cause of Salt failures on servers, datacenters and groups of datacenters. This system is able to correlate failures with git commits, external service failures and ad hoc releases. The result of this has been a reduction in the duration of software release delays, and an overall reduction in toilsome, repetitive triage for SRE.

To start, we will go into the basics of the Cloudflare network and how Salt operates within it. And then we’ll get to how we solved the challenge Continue reading

Connecting to production: the architecture of remote bindings

Remote bindings are bindings that connect to a deployed resource on your Cloudflare account instead of a locally simulated resource – and recently, we announced that remote bindings are now generally available. 

With this launch, you can now connect to deployed resources like R2 buckets and D1 databases while running Worker code on your local machine. This means you can test your local code changes against real data and services, without the overhead of deploying for each iteration. 

In this blog post, we’ll dig into the technical details of how we built it, creating a seamless local development experience.

A key part of the Cloudflare Workers platform has been the ability to develop your code locally without having to deploy it every time you wanted to test something – though the way we’ve supported this has changed greatly over the years. 

We started with wrangler dev running in remote mode. This works by deploying and connecting to a preview version of your Worker that runs on Cloudflare’s network every time you make a change to your code, allowing you to test things out as you develop. However, remote mode isn’t perfect — Continue reading

A closer look at Python Workflows, now in beta

Developers can already use Cloudflare Workflows to build long-running, multi-step applications on Workers. Now, Python Workflows are here, meaning you can use your language of choice to orchestrate multi-step applications.

With Workflows, you can automate a sequence of idempotent steps in your application with built-in error handling and retry behavior. But Workflows were originally supported only in TypeScript. Since Python is the de facto language of choice for data pipelines, artificial intelligence/machine learning, and task automation – all of which heavily rely on orchestration – this created friction for many developers.

Over the years, we’ve been giving developers the tools to build these applications in Python, on Cloudflare. In 2020, we brought Python to Workers via Transcrypt before directly integrating Python into workerd in 2024. Earlier this year, we built support for CPython along with any packages built in Pyodide, like matplotlib and pandas, in Workers. Now, Python Workflows are supported as well, so developers can create robust applications using the language they know best.

Imagine you’re training an LLM. You need to label the dataset, feed data, wait for the model to run, evaluate the loss, adjust the model, and repeat. Without automation, Continue reading