CVE-2026-126068: Action Mailbox routes incoming emails to controller-like mailboxes for processing in Rails
Affects railsSource GCVE Database
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
Thin evidence
One scorer or none| CNA (GitHub_M) | CVSS 3.1 | 3.7 |
|---|
- 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:NExploitation evidence
Disclosed: evidence found.
CVE published 10 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10railspkg:deb/ubuntu/rails?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu Pro 22.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=esm-apps/jammyOther threats | Affected
| Fixed in– |
Ubuntu Pro 20.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=esm-apps/focalOther threats | Affected
| Fixed in– |
Ubuntu Pro 18.04 LTSrailspkg:deb/ubuntu/rails?arch=source&distro=esm-apps/bionicOther threats | Affected
| 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
- ubuntu.com/security/CVE-2026-126068 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-126068 (opens in a new tab)
- github.com/rails/rails/security/advisories/GHSA-5957-c7qm-m469 (opens in a new tab)
- github.com/rails/rails/commit/4aa2ec66822bc4eb8b341a0608f1c90a3e371a34 (opens in a new tab)
- github.com/rails/rails/commit/c3a295c5c22266e8ec4d0e664e6923a299235e7a (opens in a new tab)
- github.com/rails/rails/releases/tag/v8.0.5.2 (opens in a new tab)
- github.com/rails/rails/releases/tag/v8.1.4.1 (opens in a new tab)