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VulnerabilityPublished

CVE-2026-128069: rails-html-sanitizer · Possible XSS via shared scrubber state in concurrent calls

Affects rails-html-sanitizerSource GCVE Database

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Authoritative record:CVE-2026-128069· Medium 4.7

Not known to be exploited · CVSS 4.7 Medium : upgrade to 1.7.2 when convenient.

Data as of 13 Nov 2026, 20:19 UTC

CVSS 3.1 base score
4.7Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitHub_M)CVSS 3.14.7
Patch
Available – fixed in 1.7.2
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Upgrade rails-html-sanitizer to 1.7.2.

Affected software

ProductAffectedFixed in
RubyGemsrails-html-sanitizerAffected
  • <1.7.2
Fixed in
  • 1.7.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade rails-html-sanitizer to version 1.7.2 or later, where this concurrency issue is fixed. Alternatively, ensure that all sanitize calls use the same allowlist or pass a scrubber instance created per call (e.g., Rails::HTML::PermitScrubber.new with tags and attributes set) instead of using the tags: and attributes: options. Applications running single-threaded or using a single sanitizer configuration everywhere are not vulnerable.

Description

A concurrency issue in rails-html-sanitizer versions prior to 1.7.2 allows cross-site scripting (XSS) via shared scrubber state during concurrent sanitize calls with differing allowlists. The vulnerability arises because the PermitScrubber instance is shared and its tags and attributes are reassigned without synchronization, causing one request's sanitizer to use another's permissive allowlist. This affects multi-threaded Ruby on Rails applications using the default sanitizer configuration. The issue is fixed in version 1.7.2.

References

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