VulnerabilityDeferred

CVE-2025-61152

python-jose thru 3.3.0 allows JWT tokens with 'alg=none' to be decoded and accepted without any cryptographic signature verification.

MEDIUM 6.5EPSS 0.32%

Does this matter?

Lower severity and a low EPSS score (0.32%). Track it; it rarely justifies an emergency change on its own.

Description

python-jose thru 3.3.0 allows JWT tokens with 'alg=none' to be decoded and accepted without any cryptographic signature verification. A malicious actor can craft a forged token with arbitrary claims (e.g., is_admin=true) and bypass authentication checks, leading to privilege escalation or unauthorized access in applications that rely on python-jose for token validation. This issue is exploitable unless developers explicitly reject 'alg=none' tokens, which is not enforced by the library. NOTE: all parties agree that the issue is not relevant because it only occurs in a "verify_signature": False situation.

CVSS 3.1: 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
EPSS: 0.32% probability · 25th percentile
CISA KEV: Not listed
Weakness: CWE-269
Source: cve@mitre.org

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.