Is there a public exploit for CVE-2026-102269?

No public exploit for CVE-2026-102269 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-102269?

CVE-2026-102269 scores CVSS 5.4 (v3.1), rated medium. EPSS puts the chance of exploitation in the next 30 days at 0.22%.

What does CVE-2026-102269 affect?

CVE-2026-102269 affects jpadilla PyJWT.

5.4 Medium

PyJWT is a Python implementation of JSON Web Token standards.

CVE-2026-102269

Summary PyJWT 2.13.0 accepts compact JWS signature segments containing characters that are not in the Base64URL alphabet. Appending !!!! to a valid signature does not change the decoded signature bytes or authenticated claims, but it changes the serialized token and its SHA-256 hash. An application that indexes logout or revocation state by the raw token therefore rejects the logged-out token and accepts its no-key alternate serialization. This report separates two issues: permissive compact-JWS decoding is the library behavior, while using raw serialized JWT text as a security identity is a dangerous application composition. A jti-indexed control blocks both representations. Affected Version Confirmed with PyJWT 2.13.0 on CPython 3.13. The mutation changes only the signature segment and requires no signing key. End-to-End Reproduction bash .venv-research/bin/python 06-practical-testing/revocation-bypass-lab.py The loopback-only lab performs: 1. Issue a valid HS256 admin token. 2. Access /protected successfully. 3. Log out the canonical token and store SHA256(rawtoken). 4. Confirm canonical replay returns HTTP 401. 5. Append !!!! to only the signature segment. 6. Confirm the…

Assessment

CVSS: 5.4 (v3.1)
Severity: Medium
EPSS: 0.22% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 28 September 2026
Last updated: 6 October 2026
Affected: jpadilla · pyjwt · PyJWT
Weakness: CWE-180
Assigner: security-advisories@github.com

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

At the source

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