CVE-2026-67448: Mailpit: WebSocket origin check bypass via percent-encoded path (regression of CVE-2026-22689)

August 20, 2026 (updated September 2, 2026)

The cross-site WebSocket hijacking fix was reimplemented as an origin check gated on a raw-URI prefix test, but Go’s ServeMux routes on the percent-decoded path, so requesting /%61pi/events reaches the WebSocket handler while skipping the only origin control, and the upgrader itself accepts every origin. Confirmed at HEAD 408b30d. Affects 1.29.0 through 1.30.5.

References

github.com/advisories/GHSA-8r62-w5wh-fc5m
github.com/axllent/mailpit/commit/fbe5e006c3f1682b819df58b4a932d7a84920be9
github.com/axllent/mailpit/releases/tag/v1.30.6
github.com/axllent/mailpit/security/advisories/GHSA-8r62-w5wh-fc5m
nvd.nist.gov/vuln/detail/CVE-2026-67448

Code Behaviors & Features

Detect and mitigate CVE-2026-67448 with GitLab Dependency Scanning

Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Dependency Scanning using SBOM also detects vulnerabilities from proprietary advisories that this site does not include. Learn more about Dependency Scanning using SBOM →