CVE-2026-102272 PyJWT - Authentication Bypass

PyJWT 2.13.0 to < 2.14.0 contains an authentication bypass caused by improper normalization of Unicode byte-order marks in raw-JWK detection in HMACAlgorithm.prepare_key, letting attackers forge tokens using public keys, exploit requires use of mixed-algorithm verification with public JWK prefixed by UTF-8 BOM.

CVSS base score 7.4 /10
High
CISA KEV
Not listed
Public exploit
Proof of concept available
EPSS
0.18% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Authentication Bypass
Impact
Broken Authentication
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Published
28 September 2026
Updated
15 October 2026
Weakness
CWE-347

Vendor fix

Upgrade to version 2.14.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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