Improper Verification of Cryptographic Signature Affecting pyjwt package, versions [2.13.0,2.14.0)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-PYJWT-20247305
- published29 Sept 2026
- disclosed28 Sept 2026
- creditCharles Vosburgh
Introduced: 28 Sep 2026
NewCVE-2026-102273 (opens in a new tab)How to fix?
Upgrade PyJWT to version 2.14.0 or higher.
Overview
PyJWT is a Python implementation of RFC 7519.
Affected versions of this package are vulnerable to Improper Verification of Cryptographic Signature via the prepare_key method in jwt/algorithms.py, where a public JWK container (such as a JWK Set with a kty member nested inside a JSON array or deeply nested object) is not rejected when supplied as an HMAC secret. An attacker who controls the key material can pass a public asymmetric key as the HMAC secret, enabling signature forgery by exploiting the algorithm confusion between asymmetric and symmetric key types.