vulnerability · Tue 29 Sep 2026 · 23:43 UTC
GHSA-9j54-fg26-wv3r: PyJWT: PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation
Filed UTCSource GTH ↗
A service that verifies HS256 tokens using an empty oct JWK through PyJWK, including a PyJWK obtained from PyJWKSet, can therefore accept attacker-generated tokens as authenticated. PyJWT 2.13.0 rejects an empty HMAC key when it is supplied through the raw str/bytes key path, but accepts the same zero-length key when it is supplied as a symmetric PyJWK. An oct JWK containing an empty Base64URL key value: ``json {"kty":"oct","k":""} ` is decoded to b""`. …
Signals
as the pipeline stamped them- High
- High-risk vulnerability — CVSS 7.4
CVE
KEV from CISA · EPSS from FIRST| Id | KEV | EPSS | Reference |
|---|---|---|---|
| CVE-2026-102266 | — | 0.18% | NVD ↗ |
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