Server-Side Request Forgery (SSRF) in pyjwt - #VU150527
Published: September 17, 2026
Vulnerability identifier: #VU150527
CSH Severity: Medium
CVSS v4: 9.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-918
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose sensitive request headers and cause forged JWT acceptance.
The vulnerability exists due to improper validation of redirect destinations in PyJWKClient when fetching JWKS from an attacker-influenced configured endpoint. A remote attacker can cause the endpoint to return a redirect to a different host to disclose sensitive request headers and cause forged JWT acceptance.
A token kid alone does not trigger the issue.
Affected software
pyjwt
Remediation
Install security update from vendor's website.
pyjwt - update to 2.14.0