CVE-2026-59157Network attack vectorHinoki check available

Authentication bypass via unfiltered identity header

Published Sep 15, 2026 · Updated Sep 15, 2026

Authentication bypass in Nicolas Carlier webhookd before 1.22.0 allows remote attackers to impersonate users via a forged HTTP header. HTTPParamsToShellVars in pkg/api/index.go converts every incoming header into a shell variable when htpasswd authentication is disabled, including attacker-controlled X-WebAuthn-User values. Exploitation requires an unhardened reverse proxy and a hook script that trusts the variable, exposing only resources available to the impersonated identity.

CVSS severity6.5
Medium
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Authentication bypass in Nicolas Carlier webhookd before 1.22.0 allows remote attackers to impersonate users via a forged HTTP header. HTTPParamsToShellVars in pkg/api/index.go converts every incoming header into a shell variable when htpasswd authentication is disabled, including attacker-controlled X-WebAuthn-User values. Exploitation requires an unhardened reverse proxy and a hook script that trusts the variable, exposing only resources available to the impersonated identity.

The record

CVE
CVE-2026-59157
Published
Sep 15, 2026
Updated
Sep 15, 2026
Vendor
Nicolas Carlier
Product
webhookd
Classifications
CWE-807, CWE-290, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.22

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nicolas Carlier · webhookdversion=< 1.22

Published CVSS scores

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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-807Reliance on Untrusted Inputs in a Security Decision
CWE-290Authentication Bypass by Spoofing
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo