Cross-site Scripting (XSS) Affecting ruby3.4-activesupport package, versions <8.1.2.1-r0


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.01% (3rd percentile)

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  • Snyk IDSNYK-MINIMOSLATEST-RUBY34ACTIVESUPPORT-15793299
  • published27 Mar 2026
  • disclosed24 Mar 2026

Introduced: 24 Mar 2026

NewCVE-2026-33170  (opens in a new tab)
CWE-79  (opens in a new tab)

How to fix?

Upgrade Minimos:latest ruby3.4-activesupport to version 8.1.2.1-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream ruby3.4-activesupport package and not the ruby3.4-activesupport package as distributed by Minimos. See How to fix? for Minimos:latest relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1