CVE-2026-102272: PyJWT is a Python implementation of JSON Web Token standards

This week

HIGH 7.4REMOTEDOWNGRADE

CVE-2026-102272 is a high-severity flaw (CVSS 7.4) affecting pyjwt. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.prepare_key in jwt/algorithms.py is affected because raw-JWK detector does not normalize accepted Unicode byte-order marks before checking for JSON. This occurs when a public JWK is prefixed with a UTF-8 BOM and used in a mixed-algorithm verification path. As a result, public JWK bypasses asymmetric-key detection and becomes the HMAC secret. Cons

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.4 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 88%)
CISA exploited list	No
Weakness	CWE-347
Published	2026-09-28
Last modified	2026-10-06

Publisher (CNA): GitHub, Inc. · Vendor: pyjwt project

Last updated 2026-10-06 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-28 21:17 UTCPublished CVE record published
2026-10-06 18:34 UTCUpdated Record last modified

pyjwt project pyjwt DOWNGRADE

Affected: 2.13.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.13.0

1. Check installed version

apt-cache policy pyjwt || rpm -q pyjwt || pyjwt --version

2. No fixed release: DOWNGRADE to a release before 2.13.0 (Debian / Ubuntu)

apt-cache madison pyjwt sudo apt install pyjwt=<VERSION_BEFORE_2.13.0> sudo apt-mark hold pyjwt

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list pyjwt sudo dnf downgrade pyjwt-<VERSION_BEFORE_2.13.0> sudo dnf versionlock add pyjwt

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-102272?

pyjwt: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-102272 being exploited?

CVE-2026-102272 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-102272 affect?

CVE-2026-102272 affects pyjwt. Severity is high (CVSS 7.4). PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.prepare_key in jwt/algorithms.py is affected because raw-JWK detector does not normalize accepted Unicode byte-order marks before checking

How urgent is CVE-2026-102272?

Priority 39/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

Related CVEs

CVE-2026-48526 HIGH 7.4 UPGRADE PyJWT is a JSON Web Token implementation in Python
CVE-2026-48524 LOW 3.7 UPGRADE PyJWT is a JSON Web Token implementation in Python
CVE-2026-48522 MEDIUM 4.2 UPGRADE PyJWT is a JSON Web Token implementation in Python
CVE-2026-48525 MEDIUM 5.3 UPGRADE PyJWT is a JSON Web Token implementation in Python
CVE-2026-48523 MEDIUM 5.4 UPGRADE PyJWT is a JSON Web Token implementation in Python

References

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