---
title: "CVE-2026-102271: PyJWT - Authentication Bypass"
description: "PyJWT 2.4.0 to 2.14.0 contains an authentication bypass caused by improper handling of DER-encoded public keys in HMACAlgorithm.prepare_key, letting attackers forge authenticated HMAC tokens when mixing HMAC and asymmetric algorithms, exploit requires attacker knowledge of the public key."
url: https://panop.io/threat-heartbeat/CVE-2026-102271/
---

# CVE-2026-102271 PyJWT - Authentication Bypass

PyJWT 2.4.0 to 2.14.0 contains an authentication bypass caused by improper handling of DER-encoded public keys in HMACAlgorithm.prepare\_key, letting attackers forge authenticated HMAC tokens when mixing HMAC and asymmetric algorithms, exploit requires attacker knowledge of the public key.

CVSS base score 7.4 /10

High

CISA KEV

Not listed

Public exploit

Proof of concept available

EPSS

0.18% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-102271)

## Details

Type

Authentication Bypass

Impact

Broken Authentication

CVSS vector

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

Published

28 September 2026

Updated

15 October 2026

Weakness

[CWE-347](https://cwe.mitre.org/data/definitions/347.html)

## Vendor fix

Update to version 2.14.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-102271](https://nvd.nist.gov/vuln/detail/CVE-2026-102271)
- [https://github.com/jpadilla/pyjwt/commit/2798504fa2663364573cf2d1043d8d7fef389499](https://github.com/jpadilla/pyjwt/commit/2798504fa2663364573cf2d1043d8d7fef389499)
- [https://github.com/jpadilla/pyjwt/releases/tag/2.14.0](https://github.com/jpadilla/pyjwt/releases/tag/2.14.0)
- [https://github.com/jpadilla/pyjwt/security/advisories/GHSA-p4g4-x82p-q773](https://github.com/jpadilla/pyjwt/security/advisories/GHSA-p4g4-x82p-q773)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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