Rails Active Support has a possible XSS vulnerability in SafeBuffer#%
Published: March 23, 2026
SECURITY IDENTIFIERS
- CVE: CVE-2026-33170 (NVD)
- GHSA: GHSA-89vf-4333-qx8v
- Vendor Advisory: https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v
GEM
FRAMEWORK
PATCHED VERSIONS
~> 7.2.3, >= 7.2.3.1
~> 8.0.4, >= 8.0.4.1
>= 8.1.2.1
DESCRIPTION
Impact
SafeBuffer#% does not propagate the @html_unsafe flag to the newly created buffer.
If a SafeBuffer is mutated in place (e.g. via gsub!) and then formatted with % using untrusted arguments,
the result incorrectly reports html_safe? == true, bypassing ERB auto-escaping and possibly leading to XSS.
Releases
The fixed releases are available at the normal locations.
RELATED
- https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v
- https://github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7
- https://github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2db
- https://github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035beb
- https://github.com/rails/rails/releases/tag/v7.2.3.1
- https://github.com/rails/rails/releases/tag/v8.0.4.1
- https://github.com/rails/rails/releases/tag/v8.1.2.1
- https://github.com/advisories/GHSA-89vf-4333-qx8v