webhookd: Unrestricted HTTP Header to Shell Variable Injection

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS

• CVE-2026-59157: 0.60% estimated exploitation activity in the next 30 days; percentile 48.53 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Description Before 1.22, if the Basic Auth (htpasswd) middleware was not configured, all incoming HTTP headers were blindly forwarded to the webhook script execution environment as shell variables. While the Basic Auth middleware correctly strips the authentication header (X-WebAuthn-User) from the incoming request before conditionally re-injecting it on successful authentication, disabling Basic Auth left the system vulnerable if deployed behind an unhardened reverse proxy. Impact If an upstream reverse proxy is not properly hardened to strip client-provided authentication headers, an attacker could manually supply these headers (e.g., X-WebAuthn-User). A webhook script relying on this forwarded header for privilege elevation or identity verification could therefore be exploited to bypass security controls and impersonate other users. Mitigation The WHDALLOWEDUPSTREAMHEADERS configuration setting has been introduced to enforce a strict allowlist of HTTP headers that can be converted…

Published by the source

9 Sep 2026, 23:47 UTC

Last modified by the source

17 Sep 2026, 17:30 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-v25g-mvwr-f5fp

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6451

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-v25g-mvwr-f5fp

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# Patch Next advisory brief: CVE-2026-59157

Advisory: webhookd: Unrestricted HTTP Header to Shell Variable Injection
IDs: CVE-2026-59157, GHSA-v25g-mvwr-f5fp
Record: https://patchnext.com/advisories/cve-2026-59157 (revision 3, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/ncarlier/webhookd 1.22.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/ncarlier/webhookd: affected < 1.22.0; fixed in 1.22.0

## Suggested inspection (read-only)
- Go github.com/ncarlier/webhookd: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/ncarlier/webhookd.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-v25g-mvwr-f5fp (OSV record GHSA-v25g-mvwr-f5fp lists affected ranges: Go github.com/ncarlier/webhookd >=0 <1.22.0 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6451 (OSV record GO-2026-6451 lists affected ranges: Go github.com/ncarlier/webhookd >=0 <1.22.0 (fixed))
- Verified: https://github.com/advisories/GHSA-v25g-mvwr-f5fp (GitHub-reviewed advisory GHSA-v25g-mvwr-f5fp lists affected ranges: Go github.com/ncarlier/webhookd >=0 <1.22.0)

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