Bug 2521051 (CVE-2026-54789)

Summary: CVE-2026-54789 mod_auth_openidc: mod_auth_openidc: Denial of Service via malformed state cookie parsing
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in mod_auth_openidc, an OpenID Connect Relying Party module for Apache HTTP servers. A remote attacker can exploit this vulnerability by sending a specially crafted HTTP request with a malformed state cookie. This can lead to an out-of-bounds read and a one-byte out-of-bounds write during state cookie parsing, primarily resulting in a Denial of Service (DoS) for the affected server.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2523272    
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Description OSIDB Bzimport 2026-08-21 16:33:11 UTC
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.