Worker crashes via unterminated state-cookie scan
Published Aug 21, 2026 · Updated Aug 21, 2026
Out-of-bounds access in OpenIDC mod_auth_openidc before 2.4.19.4 allows remote attackers to crash Apache workers via malformed cookies. The oidc_state_cookies_parse_token() loop scans a state-prefixed cookie token for '=' without stopping at the NUL terminator, then overwrites the byte where the scan stops. An unauthenticated client can reach the parser before session or state validation; the read can hit an unmapped page and crash a worker, while the one-byte NUL write corrupts adjacent memory without disclosed code execution.
Summary
What happened
Out-of-bounds access in OpenIDC mod_auth_openidc before 2.4.19.4 allows remote attackers to crash Apache workers via malformed cookies. The oidc_state_cookies_parse_token() loop scans a state-prefixed cookie token for '=' without stopping at the NUL terminator, then overwrites the byte where the scan stops. An unauthenticated client can reach the parser before session or state validation; the read can hit an unmapped page and crash a worker, while the one-byte NUL write corrupts adjacent memory without disclosed code execution.
The record
- CVE
- CVE-2026-54789
- Published
- Aug 21, 2026
- Updated
- Aug 21, 2026
- Vendor
- OpenIDC
- Product
- mod_auth_openidc
- Classifications
- CWE-125, CWE-787, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 21, 2026CVE publishedPublication date reported by the CVE source.
- Aug 21, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=< 2.4.19.4
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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