What’s Vulnerable › Vulnerabilities

CVE-2026-48526: PyJWT: Public-key JWK accepted as HMAC secret enables forged HS256 tokens when mixed families are allowed

• Severity: high (CVSS 7.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-05-28 · updated 2026-10-26
• Weakness: CWE-287

Description

PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, when the verifier is decoding JSON Web Tokens, while supporting both asymmetric and HMAC algorithms, the library does not validate use of JSON Web Keys in HMAC algorithm, allowing attacker to use the issuer public key as the secret key for HMAC algorithm. This vulnerability is fixed in 2.13.0.

Affected products

• jpadilla pyjwt: before 2.13.0 — fixed in 2.13.0

How to fix

Upgrade to a fixed version: jpadilla pyjwt 2.13.0. Check the vendor advisory for mitigations.

References

• https://github.com/jpadilla/pyjwt/security/advisories/GHSA-xgmm-8j9v-c9wx
• https://access.redhat.com/errata/RHSA-2026:25902
• https://access.redhat.com/errata/RHSA-2026:25928
• https://access.redhat.com/errata/RHSA-2026:26206
• https://access.redhat.com/errata/RHSA-2026:28571
• https://access.redhat.com/errata/RHSA-2026:30076
• https://access.redhat.com/errata/RHSA-2026:30088
• https://access.redhat.com/errata/RHSA-2026:30089
• https://access.redhat.com/errata/RHSA-2026:33683
• https://access.redhat.com/errata/RHSA-2026:34160
• https://access.redhat.com/errata/RHSA-2026:34365
• https://access.redhat.com/errata/RHSA-2026:34374

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