CVE-2026-48522

medium

Published 2026-05-28 · Modified 2026-05-28

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CVSS v3

4.2

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

CVSS v4 NEW

—

not yet in upstream

VIR risk

4.2

Description

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.

Predictions

Exploit likelihood

52%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

OS impact

OS	Version	Status
sles		affected
debian	bookworm	affected
debian	bullseye	affected
debian	forky	affected
debian	sid	affected
debian	trixie	affected

References

CWEs

CWE-441 CWE-918

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.