CVSS 3.1
3.7 lowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:NCVE-2026-126068 rails rails: Authentication Bypass by Capture-replay
Low (3.7) in rails rails. EPSS 0.3% estimated probability of exploitation activity in the next 30 days. Fixed in actionmailbox 8.0.5.2, 8.1.4.1.
On this page
Action Mailbox routes incoming emails to controller-like mailboxes for processing in Rails. Prior to 8.1.4.1 and 8.0.5.2, the Action Mailbox Mailgun ingress authenticates a request with an HMAC of the timestamp and token parameters concatenated without a separator, and ActionMailbox::Ingresses::Mailgun::InboundEmailsController::Authenticator#recent? rejects only timestamps more than 2 minutes in the past. Because the signature does not fix the boundary between the two values, a captured signed request can be presented with a timestamp far in the future, which the ingress then accepts indefinitely. An attacker who obtains one signed Mailgun webhook request, but not the signing key, could submit arbitrary inbound email that Action Mailbox processes as genuine, possibly leading to forged messages attributed to the sender of the attacker's choosing. Applications that receive inbound email through the Action Mailbox Mailgun ingress are affected. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.
Severity
- EPSS
- 0.3% estimated probability of exploitation activity in the next 30 days; 28th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CISA's assessment (SSVC)
- Exploitation: none · Automatable: no · Technical impact: partial, assessed 2026-11-10. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
- CWE
- CWE-294 Authentication Bypass by Capture-replay
- OWASP Top 10
- A07:2025 Authentication Failures
- Published
- Modified
- Assigned by
- GitHub_M (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
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Affected
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| rails | >= 8.1, < 8.1.4.1 |
| rails | < 8.0.5.2 |
Fix and patched versions
actionmailbox(RubyGems): fixed in 8.1.4.1, 8.0.5.2
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-5957-c7qm-m469 | RubyGems | actionmailbox | >=8.1.0.beta1 <8.1.4.1 | 8.1.4.1 |
| GHSA-5957-c7qm-m469 | RubyGems | actionmailbox | <8.0.5.2 | 8.0.5.2 |
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Debian | 12, 13, 14 | rails | no fix listed | DEBIAN-CVE-2026-126068 |
| Ubuntu | 24.04:LTS, 26.04:LTS, 26.10 and 4 more | rails | no fix listed | UBUNTU-CVE-2026-126068 |
From the distributions' data via OSV.dev: the Debian Security Tracker; Ubuntu Security Notices © Canonical Ltd., CC BY-SA 4.0. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Debian · Ubuntu.
Attack patterns (CAPEC)
- CAPEC-60 Reusing Session IDs (aka Session Replay) Likelihood: High · Severity: High
- CAPEC-94 Adversary in the Middle (AiTM) Likelihood: High · Severity: Very High
- CAPEC-102 Session Sidejacking Likelihood: High · Severity: High
- CAPEC-509 Kerberoasting Severity: High
- CAPEC-555 Remote Services with Stolen Credentials Severity: Very High
- CAPEC-561 Windows Admin Shares with Stolen Credentials
- CAPEC-644 Use of Captured Hashes (Pass The Hash) Likelihood: Medium · Severity: High
- CAPEC-645 Use of Captured Tickets (Pass The Ticket) Likelihood: Low · Severity: High
- CAPEC-652 Use of Known Kerberos Credentials Likelihood: Medium · Severity: High
- CAPEC-701 Browser in the Middle (BiTM) Likelihood: Medium · Severity: High
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.
References
- https://github.com/rails/rails/commit/4aa2ec66822bc4eb8b341a0608f1c90a3e371a34
- https://github.com/rails/rails/commit/c3a295c5c22266e8ec4d0e664e6923a299235e7a
- https://github.com/rails/rails/releases/tag/v8.0.5.2
- https://github.com/rails/rails/releases/tag/v8.1.4.1
- https://github.com/rails/rails/security/advisories/GHSA-5957-c7qm-m469