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CVE-2026-126072VulnerabilityPublished Updated

Rails: Prior to 8.1.4.1 and 8.0.5.2, ActionController::Live::Buffer#close pushes its end-of-stream marker onto the

Affects railsSource GCVE Database

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Authoritative record:CVE-2026-126072· Medium 5.9

Not known to be exploited · CVSS 5.9 Medium · fixed in 8.1.4.1 : update rails when convenient.

Data as of 13 Nov 2026, 22:32 UTC

CVSS 3.1 base score
5.9Medium
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 3.15.9
Patch
Available – fixed in 8.1.4.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

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 Ruby on Rails to version 8.1.4.1 or 8.0.5.2 or later, where this issue is fixed. No other mitigations are indicated by the vendor advisory.

Description

A denial-of-service vulnerability exists in Ruby on Rails versions prior to 8.1.4.1 and 8.0.5.2 in the ActionController::Live::Buffer component. The issue occurs when the buffer's end-of-stream marker push blocks due to a full response queue while holding a monitor, causing threads to wait indefinitely and potentially exhaust server threads. This affects applications streaming responses with ActionController::Live, including send_stream, and those serving large files via Active Storage proxy mode. The vulnerability is fixed in versions 8.1.4.1 and 8.0.5.2.

References

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