CVE-2026-9537

Mojo::JWT versions before 1.02 for Perl verify HMAC signatures with a non-constant-time string comparison. The decode() method compares the supplied signature to the recomputed HMAC with Perl's eq operator, which stops at the first differing byte, so the comparison time varies with the number of matching leading bytes. A caller that decodes attacker supplied tokens leaks the expected signature through this timing variation, which can be aggregated over many requests to recover the signature and forge a token.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/jberger/Mojo-JWT/commit/b8aefb846613e44b5b12bc170898ffd5b05094a2.patch
http://www.openwall.com/lists/oss-security/2026/07/17/11

Configurations

No configuration.

History

No history.

Information

Published : 2026-07-17 16:17

Updated : 2026-07-20 20:16

NVD link : CVE-2026-9537

Mitre link : CVE-2026-9537

CVE.ORG link : CVE-2026-9537

JSON object : View

Products Affected

No product.

CWE

CWE-208

Observable Timing Discrepancy

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