CVE-2026-126068
What it is
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.
At a glance
- Exploitability
- Can be exploited over the network without logging in. Limited direct impact.
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: not scored yet.
- Severity: 3.7 LOW (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Weakness
- CWE-294
- Record status
- Received
Attack profile CVSS 3.1 · 3.7
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-126068.md and follow it. Check whether this project is affected by CVE-2026-126068. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- 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
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