WAF mitigations for Spring4Shell


A set of high profile vulnerabilities have been identified affecting the popular Java Spring Framework and related software components - generally being referred to as Spring4Shell.
Four CVEs have been released so far and are being actively updated as new information emerges. These vulnerabilities can result, in the worst case, in full remote code execution (RCE) compromise:
- CVE-2022-22947 - [official VMware post]
- CVE-2022-22950 - [official VMware post]
- CVE-2022-22963 - [official Spring project post]
- CVE-2022-22965 - [official Spring project post]
Customers using Java Spring and related software components, such as the Spring Cloud Gateway, should immediately review their software and update to the latest versions by following the official Spring project guidance.
The Cloudflare WAF team is actively monitoring these CVEs and has already deployed a number of new managed mitigation rules. Customers should review the rules listed below to ensure they are enabled while also patching the underlying Java Spring components.
CVE-2022-22947
A new rule has been developed and deployed for this CVE with an emergency release on March 29:
Managed Rule Spring - CVE:CVE-2022-22947
- WAF rule ID:
e777f95584ba429796856007fbe6c869 - Legacy rule ID:
100522
Note that the above rule is disabled by Continue reading

