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VulnerabilityPublished Updated

CVE-2026-126068: Action Mailbox routes incoming emails to controller-like mailboxes for processing in Rails

Affects railsSource GCVE Database

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Authoritative record:CVE-2026-126068· Low 3.7

Not known to be exploited · CVSS 3.7 Low · fixed in 8.1.4.1 : update rails when convenient.

Data as of 13 Nov 2026, 22:32 UTC

CVSS 3.1 base score
3.7Low
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 3.13.7
Patch
Available – fixed in 8.1.4.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/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 or later, where this vulnerability is fixed. No other mitigation is indicated by the vendor advisory.

Description

A vulnerability in Rails Action Mailbox's Mailgun ingress allows an attacker to reuse a captured signed webhook request with a manipulated timestamp far in the future. This flaw exists because the HMAC signature concatenates timestamp and token without a separator, and the timestamp validation only rejects timestamps more than 2 minutes in the past, accepting future timestamps indefinitely. This can enable an attacker to submit forged inbound emails processed as genuine by the application. The issue affects Rails versions prior to 8.1.4.1 and 8.0.5.2 and is fixed in these versions.

References

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