Staging Environment: Content and features may be unstable or change without notice.
Advisory details: ruby_advisory_db / gems/activesupport/CVE-2026-33170
Advisory ID ruby_advisory_db/gems/activesupport/CVE-2026-33170
Aliases CVE-2026-33170
GHSA-89vf-4333-qx8v
Summary Rails Active Support has a possible XSS vulnerability in SafeBuffer#% ### 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.
Status Published
Exploitability 0.5
Weighted Severity 0.0
Risk
Affected and Fixed Packages Package Details
Introduced and Fixed Package Commit Patches Package Commit Patches Details
Weaknesses (0)
There are no known CWE.
System Score Found at
cvssv4 5.3
Reference id Reference type URL
GHSA-89vf-4333-qx8v https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v
No exploits are available.

No EPSS data available for this advisory.

Patch URL
There are no known patches.
There are no known vectors.

Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-03-25T19:20:16Z/

Decision: Track

Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2026/33xxx/CVE-2026-33170.json

Source Advisory: vulnrichment/CVE-2026-33170

View SSVC decision tree 
[{'Exploitation': 'none'},
 {'Automatable': 'no'},
 {'Technical Impact': 'partial'},
 {'Mission Prevalence': 'minimal'},
 {'Public Well-being Impact': 'material'},
 {'Mission & Well-being': 'medium'}]