Medium 5.3Published Sep 28, 2026

CVE-2026-101917PyJWT: PyJWKClient still amplifies unauthenticated JWKS fetches on unknown kid values (incomplete fix of CVE-2026-48524)

Updated under an hour ago (2026-10-19 07:00 UTC)

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It affects jpadilla pyjwt and 1 other product. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.42%, higher than 34% of scored CVEs.

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Every CVE for jpadilla pyjwt

Exploited in the last 30 days

PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, PyJWT get_signing_key_from_jwt is affected because unknown kid misses force refreshes without a negative cache or minimum refresh interval. This occurs when unauthenticated tokens repeatedly use the same unknown kid or varying kid values absent from the cached JWKS. As a result, each cache miss causes PyJWKClient to refresh the JWKS. Consequently, attacker traffic can amplify outbound requests to the configured JWKS endpoint. This issue is fixed in version 2.14.0.

CVSS: 5.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness (CWE): CWE-770
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.42% (percentile 34)
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Sep 28, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

jpadilla pyjwt jpadilla:pyjwt (from the name)	before 2.14.0	CNA record
pyjwt_project pyjwt pyjwt_project:pyjwt	before 2.14.0	NVD

References

https://github.com/jpadilla/pyjwt/security/advisories/GHSA-2gx3-rcp4-g85qx-refsource-confirm, exploit, vendor-advisory
https://github.com/jpadilla/pyjwt/commit/ba4853a75fb9676362da17f67d0f64bd18afd4e1x-refsource-misc, patch
https://github.com/jpadilla/pyjwt/releases/tag/2.14.0x-refsource-misc, product, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.