CVE-2026-102268 PyJWT - Authentication Bypass

PyJWT < 2.14.0 contains an authentication bypass caused by is_pem_format not recognizing all PEM representations, letting attackers forge authenticated HMAC tokens when mixing HMAC and asymmetric algorithms, exploit requires supplying mutated public-key PEM as raw key bytes.

CVSS base score 9.1 /10
Critical
CISA KEV
Not listed
Public exploit
Proof of concept available
Authentication
Not required
EPSS
0.20% 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:L/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

Update 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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