CVE-2026-54789

mod_auth_openidc has out-of-bounds read and write in state cookie parsing

Published Aug 21, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
mod_auth_openidc is an OpenID Certified authentication and authorization module for the Apache 2.x HTTP server that implements the OpenID Connect Relying Party functionality. Prior to 2.4.19.4, an out-of-bounds read and a one-byte out-of-bounds write exist in the state-cookie parser of `mod_auth_openidc`. The issue is fixed in version 2.4.19.4 by stopping the scan at the string terminator so a value-less token is rejected. No in-product workarounds are available. As a stop-gap, an upstream reverse proxy or WAF that rejects or normalizes malformed `Cookie` headers (tokens lacking `=`) can reduce exposure, but upgrading is the recommended remediation.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4768-1 libapache2-mod-auth-openidc security update
Debian DSA Debian DSA DSA-6504-1 libapache2-mod-auth-openidc security update
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Openidc
Openidc mod Auth Openidc
Vendors & Products Openidc
Openidc mod Auth Openidc
Type Values Removed Values Added
Description mod_auth_openidc is an OpenID Certified authentication and authorization module for the Apache 2.x HTTP server that implements the OpenID Connect Relying Party functionality. Prior to 2.4.19.4, an out-of-bounds read and a one-byte out-of-bounds write exist in the state-cookie parser of `mod_auth_openidc`. The issue is fixed in version 2.4.19.4 by stopping the scan at the string terminator so a value-less token is rejected. No in-product workarounds are available. As a stop-gap, an upstream reverse proxy or WAF that rejects or normalizes malformed `Cookie` headers (tokens lacking `=`) can reduce exposure, but upgrading is the recommended remediation.
Title mod_auth_openidc has out-of-bounds read and write in state cookie parsing
Weaknesses CWE-125
CWE-787
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Sep 2, 2026, 7:06 PM
Reserved
Jun 15, 2026, 11:23 PM
Status
Deferred
Published
Aug 21, 2026, 4:17 PM
Modified
Oct 15, 2026, 7:10 PM
Severity
Important
Public date
Aug 21, 2026, 4:13 PM