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Vulnerability · Published Sep 28, 2026 · Assigned by GitHub_M

CVE-2026-102269PyJWT: Non-canonical signature segments enable raw-token revocation bypass

Medium 4.8

In plain English

A medium-severity security flaw in pyjwt from jpadilla. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 13% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)4.8Medium
Exploit odds (30 days)0.2%top 86.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

PyJWT is a Python implementation of JSON Web Token standards. Prior to 2.14.0, PyJWT signature segment is affected because signature segment decoding accepts characters outside the canonical Base64URL representation. This occurs when non-Base64URL characters are appended to a valid compact JWS signature segment. As a result, base64url_decode produces the same signature bytes for different serialized segments. Consequently, raw-token revocation checks can fail to recognize an equivalent modified token. This issue is fixed in version 2.14.0.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12pyjwtno fix listedDEBIAN-CVE-2026-102269
Debian:13pyjwtno fix listedDEBIAN-CVE-2026-102269
Debian:14pyjwt2.14.0-1DEBIAN-CVE-2026-102269
PyPIpyjwt2.14.0GHSA-hxm8-2xgr-2p9m
PyPIpyjwt2.14.0PYSEC-2026-4147
Ubuntu:22.04:LTSpyjwtno fix listedUBUNTU-CVE-2026-102269
Ubuntu:24.04:LTSpyjwtno fix listedUBUNTU-CVE-2026-102269
Ubuntu:26.04:LTSpyjwtno fix listedUBUNTU-CVE-2026-102269
Ubuntu:26.10pyjwtno fix listedUBUNTU-CVE-2026-102269

Affected products (as reported)

VendorProductVersions
jpadilla pyjwt < 2.14.0

Weakness: CWE-180 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

References