CVE-2026-54789
mod_auth_openidc has out-of-bounds read and write in state cookie parsing
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.
INFO
Published Date :
Aug. 21, 2026, 4:17 p.m.
Last Modified :
Aug. 21, 2026, 4:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Upgrade mod_auth_openidc to version 2.4.19.4 or later.
- Implement upstream proxy/WAF filtering for malformed Cookie headers.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-54789.
| URL | Resource |
|---|---|
| https://github.com/OpenIDC/mod_auth_openidc/commit/8017478471cc071c49aa073c5c9be652a73a8630 | |
| https://github.com/OpenIDC/mod_auth_openidc/security/advisories/GHSA-vgr5-qcpp-x2pr |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-54789 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-54789
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-54789 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-54789 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Aug. 21, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'OpenIDC', 'product': 'mod_auth_openidc', 'versions': [{'status': 'affected', 'version': '< 2.4.19.4'}]}] 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-125 Added CWE CWE-787 Added Reference https://github.com/OpenIDC/mod_auth_openidc/commit/8017478471cc071c49aa073c5c9be652a73a8630 Added Reference https://github.com/OpenIDC/mod_auth_openidc/security/advisories/GHSA-vgr5-qcpp-x2pr