CVE-2026-9537

MEDIUM

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.

CVSS v3 vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected routers (0)

No routers currently mapped to this CVE in our database.

External references

• NIST NVD
• MITRE CVE