Vulnerability · Published May 28, 2026 · Assigned by GitHub_M
CVE-2026-48524PyJWT: PyJWKClient unbounded JWKS endpoint requests via attacker-controlled kid values (DoS)
Low 3.7
In plain English
A low-severity security flaw in pyjwt from jpadilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, PyJWKClient.get_signing_key() forces a fresh HTTP request to the JWKS endpoint for every JWT with an unknown kid value, with no rate limiting. Since kid comes from the unverified token header, an attacker can trigger unlimited outbound requests. The vulnerability surfaces only when a JWKS fetch fails; an attacker can attempt to provoke that with sustained unknown-kid traffic, but the outcome depends on upstream JWKS-endpoint behavior (rate limiting, transient errors) which is beyond the attacker's control. This vulnerability is fixed in 2.13.0.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | pyjwt | no fix listed | DEBIAN-CVE-2026-48524 |
| Debian:13 | pyjwt | no fix listed | DEBIAN-CVE-2026-48524 |
| Debian:14 | pyjwt | 2.13.0-1 | DEBIAN-CVE-2026-48524 |
| PyPI | pyjwt | 2.13.0 | GHSA-fhv5-28vv-h8m8 |
| PyPI | pyjwt | 2.13.0 | PYSEC-2026-177 |
| Ubuntu:22.04:LTS | pyjwt | 2.3.0-1ubuntu0.4 | USN-8823-1 |
| Ubuntu:24.04:LTS | pyjwt | 2.7.0-1ubuntu0.2 | USN-8823-1 |
| Ubuntu:24.04:LTS | pyjwt | 2.7.0-1ubuntu0.2 | UBUNTU-CVE-2026-48524 |
| Ubuntu:25.10 | pyjwt | no fix listed | UBUNTU-CVE-2026-48524 |
| Ubuntu:26.04:LTS | pyjwt | 2.10.1-4ubuntu1.1 | USN-8823-1 |
| Ubuntu:26.04:LTS | pyjwt | 2.10.1-4ubuntu1.1 | UBUNTU-CVE-2026-48524 |
Affected products (as reported)
Weakness: CWE-460, CWE-755 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
References
- https://github.com/jpadilla/pyjwt/security/advisories/GHSA-fhv5-28vv-h8m8 x_refsource_CONFIRM