What’s Vulnerable › Vulnerabilities

CVE-2026-59157: webhookd: Unrestricted HTTP Header to Shell Variable Injection

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-15 · updated 2026-09-30
• Weakness: CWE-290

Description

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.

Affected products

• ncarlier webhookd: before 1.22

References

• 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

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