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CVE-2026-126077VulnerabilityPublished Updated

Rails: Prior to 8.1.4.1 and 8.0.5.2, When ActionDispatch::Cookies reads a signed or encrypted cookie that was written

Affects railsSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2026-126077· Medium 6.8

Not known to be exploited · CVSS 6.8 Medium · fixed in 8.1.4.1 : update rails when convenient.

Data as of 13 Nov 2026, 22:24 UTC

CVSS 3.1 base score
6.8Medium
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 3.16.8
Patch
Available – fixed in 8.1.4.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 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

Affected software

ProductAffectedFixed in
Ubuntu 26.10railspkg:deb/ubuntu/rails?arch=source&distro=stonkingOther threatsAffected
  • =2:7.2.3+dfsg-2
  • =2:7.2.3.2+dfsg-2
Fixed in–
Ubuntu 26.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=resoluteOther threatsAffected
  • =2:7.2.2.1+dfsg-7
  • =2:7.2.2.2+dfsg-2
  • =2:7.2.3+dfsg-2
Fixed in–
Ubuntu 24.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=nobleOther threatsAffected
  • =2:6.1.7.3+dfsg-2build1
  • =2:6.1.7.3+dfsg-3
Fixed in–
Ubuntu Pro 22.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=esm-apps/jammyOther threatsAffected
  • =2:6.0.3.7+dfsg-2
  • =2:6.1.4.1+dfsg-8ubuntu2
  • =2:6.1.4.1+dfsg-8ubuntu2+esm1
Fixed in–
Ubuntu Pro 20.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=esm-apps/focalOther threatsAffected
  • =2:5.2.2.1+dfsg-1ubuntu1
  • =2:5.2.3+dfsg-3
  • =2:5.2.3+dfsg-3ubuntu0.1~esm1
Fixed in–
Ubuntu Pro 18.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=esm-apps/bionicOther threatsAffected
  • 2:4.2.9-2 – 2:4.2.10-0ubuntu4+esm2
5 affected builds
Fixed in–

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

AI-suggested

Upgrade Rails to version 8.1.4.1 or 8.0.5.2 where this issue is fixed. Until then, avoid configurations that combine cookie rotation or :hybrid serializer migration with Active Storage proxy controllers behind caches that store Set-Cookie headers on public responses. Review caching policies to prevent storing Set-Cookie headers on public cacheable responses. No other vendor advisory mitigation is provided.

Description

A vulnerability in Rails prior to versions 8.1.4.1 and 8.0.5.2 affects the ActionDispatch::Cookies component. When reading signed or encrypted cookies written under a rotated secret or using a :hybrid cookie serializer migration, the cookie is rewritten in the response ignoring the skip session option. This can cause session cookies to be included in cacheable responses served by Active Storage proxy controllers, potentially exposing user sessions to other users via shared caches. The issue is fixed in Rails versions 8.1.4.1 and 8.0.5.2.

References

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