SSRF in Jpadilla Pyjwt
CVE-2026-48522
PyJWT is a JSON Web Token implementation in Python. Prior to 2.13.0, PyJWKClient passes its uri argument directly to urllib.request.urlopen() which uses Python stdlib's default OpenerDirector registering HTTPHandler, HTTPSHandler, FTPHandler, FileHandler, and DataHandler. There is currently no documented option to restrict which schemes PyJWKClient will fetch. If an application's jku URL ingestion path accepts attacker-influenced URLs (e.g., from JWT header, configuration file, OAuth flow parameter), the attacker can cause PyJWKClient to read arbitrary local files via file:// (SSRF on local filesystem), cause PyJWKClient to attempt FTP / data-URI fetches (broader SSRF surface), or forge tokens that PyJWT verifies as valid. The library does not directly return non-HTTP(S) URI contents to the attacker; the chained "plant a JWKS to forge tokens" scenario described in the original report requires additional application-layer flaws (attacker write access to a filesystem path, untrusted jku derivation) that this fix does not address. This vulnerability is fixed in 2.13.0.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.2 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.002 (11.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 12th percentile — 11.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: -0.000
Affected products
- Jpadilla Pyjwt — versions < 2.13.0
- Pyjwt Project
Weakness classification (CWE)
References
- github.com/jpadilla/pyjwt/security/advisories/GHSA-993g-76c3-p5m4 (Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-48522?
- CVE-2026-48522 is a medium-severity vulnerability in Jpadilla Pyjwt, classified under Unintended Proxy or Intermediary (Confused Deputy). CVSS score: 4.2/10. Published 2026-05-28.
- How severe is CVE-2026-48522?
- Medium severity. CVSS v3 base score is 4.2 out of 10.