GHSA-hxm8-2xgr-2p9m: pyjwt (CVE-2026-102269)

Package	Ecosystem	Affected	Fixed in
pyjwt	PyPI	<2.14.0	2.14.0

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

PyJWT versions before 2.14.0 accept compact JWS signature segments that contain characters outside the Base64URL alphabet, so appending characters such as "!!!!" yields a different serialized token with the same signature bytes and claims. An attacker who already holds a valid token and whose application keys logout or revocation state on the raw token string can replay the alternate serialization after logout. Upgrade to PyJWT 2.14.0 or later, and identify tokens by a semantic identifier such as jti rather than the raw serialized token.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
4.8	Medium	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0022, the 13th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:09 UTC First seen by agentprime
31 Oct 2026, 14:09 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.