SB2026090287 - Improper Verification of Cryptographic Signature in jwcrypto

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Main Vulnerability Database SB2026090287

SB2026090287 - Improper Verification of Cryptographic Signature in jwcrypto

Published: September 2, 2026

Security Bulletin ID SB2026090287
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Data manipulation

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Improper Verification of Cryptographic Signature (CVE-ID: CVE-2026-84185)

CWE-ID: CWE-347 - Improper Verification of Cryptographic Signature

CVSSv4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a remote user to perform unauthorized actions.

The vulnerability exists due to improper verification of cryptographic signature in JWKSet verification in jwcrypto/jws.py when verifying a General JSON Serialization JWS with a supplied JWKSet. A remote privileged user can provide a crafted JWS signed with one trusted key while declaring a different kid header to perform unauthorized actions.

Exploitation requires that the attacker possess a valid signing key in the application\'s trusted JWKSet and that the consuming application rely on kid for an authorization decision.


Remediation

Install update from vendor's website.

References