Resource exhaustion in pyjwt - #VU132104
Published: May 21, 2026
Vulnerability identifier: #VU132104
CSH Severity: Medium
CVSS v4.0: 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/E:U/U:Green
CVE-ID: N/A
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: jpadilla (José Padilla)
Affected software:
pyjwt
pyjwt
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in PyJWS.decode(), PyJWS.decode_complete(), and _load() in jwt/api_jws.py when verifying detached JWS tokens with the unencoded-payload option (b64=false). A remote attacker can send a specially crafted JWS token with an oversized Base64URL payload segment to cause a denial of service.
Practical impact depends on whether upstream components enforce request body-size limits.
Remediation
Install security update from vendor's website.