Low, CVSS 3.7RubyGemsAmendedPublished
Action Mailbox: Possible signature replay in Action Mailbox Mailgun ingress
CVE-2026-126068 · GHSA-5957-c7qm-m469
- Affected
- RubyGems actionmailbox >= 8.1.0.beta1, < 8.1.4.1; < 8.0.5.2
- Fixed in
- 8.0.5.28.1.4.1· Vendor fix available
- Issue
- Impact 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. Details The fixed releases also reject a Mailgun request whose timestamp is more than 2 minutes ahead of the server's clock, as they already did…
Recommended action: Upgrade to 8.1.4.1 or 8.0.5.2 by release line, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.