CVE-2026-59157

webhookd is a minimalist webhook server that triggers shell scripts and external processes through HTTP requests. Prior to 1.22.0, webhookd deployments without htpasswd authentication forwarded all incoming HTTP headers through HTTPParamsToShellVars in pkg/api/index.go into the hook script environment without an allowlist. When an upstream reverse proxy did not strip a client-supplied X-WebAuthn-User header and a hook script trusted that variable for identity or privilege, a remote unauthenticated attacker could spoof another user, bypass script security controls, and access or modify resources available to the impersonated identity. This issue is fixed in version 1.22.0.

• https://github.com/ncarlier/webhookd/commit/5ac66677bf7224191f1dfc51a875b09187d10beb
• https://github.com/ncarlier/webhookd/pull/121
• https://github.com/ncarlier/webhookd/releases/tag/v1.22.0
• https://github.com/ncarlier/webhookd/security/advisories/GHSA-v25g-mvwr-f5fp