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.
Metrics
Affected Vendors & Products
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References
History
Fri, 17 Jul 2026 16:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | Mojo::JWT versions before 1.02 for Perl verify HMAC signatures with a non-constant-time string comparison | |
| Weaknesses | CWE-208 | |
| References |
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MITRE
Status: PUBLISHED
Assigner: CPANSec
Published:
Updated: 2026-07-17T17:25:14.154Z
Reserved: 2026-05-25T20:46:44.842Z
Link: CVE-2026-9537
Vulnrichment
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NVD
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Redhat
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OpenCVE Enrichment
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