PT-2026-27257 · Rails+1 · Active Support+1

Published 2026-03-23 · Updated 2026-03-24 · CVE-2026-33170

Mitre

CVSS v4.0

5.3

Medium

AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Active Support is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, 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. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-33170

GHSA-89VF-4333-QX8V

Affected Products

Active Support

Rails

References · 10

• https://nvd.nist.gov/vuln/detail/CVE-2026-33170 · Security Note
• https://osv.dev/vulnerability/GHSA-89vf-4333-qx8v · Vendor Advisory
• https://github.com/rails/rails · Note
• https://github.com/rails/rails/releases/tag/v8.0.4.1 · Note
• https://github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7 · Note
• https://github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035beb · Note
• https://github.com/rails/rails/releases/tag/v7.2.3.1 · Note
• https://github.com/rails/rails/releases/tag/v8.1.2.1 · Note
• https://github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2db · Note
• https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v · Note