CVE-2026-9537

Summary

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.

Affected Software

VendorProductVersion RangeStatus
JBERGERMojo::JWT0 < 1.02affected

Weaknesses

  • CWE-208: CWE-208 Observable Timing Discrepancy

ADP Enrichment

CVE Program Container

Additional References

References