mod_auth_openidc has out-of-bounds read and write in state cookie parsing (CVE-2026-54789) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-54789

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

Answer in brief

CVE-2026-54789 records a Unknown severity vulnerability in mod_auth_openidc has out-of-bounds read and write in state cookie parsing. The current sources do not mark it as known exploited. The current feed maps OpenIDC/mod_auth_openidc (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 21, 2026Updated Aug 21, 2026Source checked Aug 21, 2026First seen by HOL Aug 21, 2026Material review Aug 21, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps OpenIDC/mod_auth_openidc (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
OpenIDC/mod_auth_openidcgeneric	< 2.4.19.4	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for OpenIDC/mod_auth_openidc.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 21, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 21, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 21, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.