Authentication bypass via variable-time signature comparison
Published Feb 8, 2024 · Updated Jun 12, 2025
Authentication bypass in Zihanggao php-jwt 1.0.0 allows remote attackers to gain unauthorized access via response-timing measurements. The JWT signature-verification path uses non-constant-time strcmp to compare the calculated signature with the token signature, exposing input-dependent timing differences. Exploitation requires repeated, sufficiently precise timing observations, and a successful bypass grants only the access assigned to the accepted token.
Summary
What happened
Authentication bypass in Zihanggao php-jwt 1.0.0 allows remote attackers to gain unauthorized access via response-timing measurements. The JWT signature-verification path uses non-constant-time strcmp to compare the calculated signature with the token signature, exposing input-dependent timing differences. Exploitation requires repeated, sufficiently precise timing observations, and a successful bypass grants only the access assigned to the accepted token.
The record
- CVE
- CVE-2024-25191
- Published
- Feb 8, 2024
- Updated
- Jun 12, 2025
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-203, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 8, 2024CVE publishedPublication date reported by the CVE source.
- Jun 12, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- cdoco php-jwt timing-attack reportproof of concept · unverified
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Technologies
Your stack
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Your stack
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