SB2026092476 - Multiple vulnerabilities in pyjwt

Description

This security bulletin contains information about 2 vulnerabilities.

1) Uncaught Exception (CVE-ID: N/A)

CWE-ID: CWE-248 - Uncaught Exception

CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to an uncaught exception in PyJWT._decode_payload when parsing a recursively nested JWT payload before signature verification. A remote attacker can submit a JWT with a deeply nested payload to cause a denial of service.

2) Insufficient verification of data authenticity (CVE-ID: N/A)

CWE-ID: CWE-345 - Insufficient Verification of Data Authenticity

CVSSv4: 8.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N]

The vulnerability allows a remote attacker to use a stolen sender-constrained access token without possessing the legitimate holder's private key.

The vulnerability exists due to insufficient verification of data authenticity in OKP private JWK import handling in jwt/algorithms.py when processing a JWK whose x and d values belong to different key pairs. A remote attacker can supply a crafted private OKP JWK to use a stolen sender-constrained access token without possessing the legitimate holder's private key.

Exploitation requires a DPoP verifier that calculates a thumbprint from x, passes the complete JWK to PyJWT for signature verification, and does not reject private JWK parameters.

Remediation

Install update from vendor's website.

References

• https://github.com/jpadilla/pyjwt/security/advisories/GHSA-42vr-xj54-vc7v
• https://github.com/jpadilla/pyjwt/commit/5fde08a6cf906aa7698de2d6391d88b73006b17b
• https://github.com/jpadilla/pyjwt/security/advisories/GHSA-x33g-cr3x-6449
• https://github.com/jpadilla/pyjwt/commit/3cd9ceec33ced359decbad75b413ad668ae6332c