# CVE-2026-48523: pyjwt: PyJWT is a JSON Web Token implementation in Python

CVE-2026-48523 is fixed in 3 products on 1 platform, first by python3-jwt 2.10.1-4ubuntu1.1, released May 28, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-48523
- Priority: Routine
- CVSS: 5.4 (medium)
- EPSS: 0.0013
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 28, 2026

## Description

PyJWT is a JSON Web Token implementation in Python. From 2.9.0 to 2.12.1, there is a verifier-side algorithm allow-list bypass when jwt.decode() or jwt.decode_complete() are called with a PyJWK key. The token header alg is checked against the caller-supplied algorithms allow-list, but signature verification is performed with the algorithm bound to the PyJWK object instead of the header algorithm. An attacker who controls a registered JWK/JWKS private key can sign with a disallowed algorithm, advertise an allowed algorithm in the JWT header, and still be accepted. The issue affects the documented PyJWKClient.get_signing_key_from_jwt(...) flow. This vulnerability is fixed in 2.13.0.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | pyjwt Debian 14 | 2.13.0-1 | [DEBIAN-CVE-2026-48523](https://patchblox.com/security/data/fix/linux/debian-cve-2026-48523.md) | May 28, 2026 |
| Linux | python-PyJWT opensuse-leap 16.0 | 2.12.1-160000.2.1 | [OPENSUSE-SU-2026:21095-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21095-1.md) | Jun 19, 2026 |
| Linux | python-PyJWT sles 15.6 | 2.4.0-150200.3.14.1 | [SUSE-SU-2026:2627-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2627-1.md) | Jun 25, 2026 |
| Linux | python-PyJWT sles 15.7 | 2.4.0-150200.3.14.1 | [SUSE-SU-2026:2627-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2627-1.md) | Jun 25, 2026 |
| Linux | python-PyJWT sles 16.0 | 2.12.1-160000.2.1 | [SUSE-SU-2026:22170-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22170-1.md) | Jun 19, 2026 |
| Linux | python3-jwt Ubuntu 26.04.1 LTS (resolute) | 2.10.1-4ubuntu1.1 | [python3-jwt 2.10.1-4ubuntu1.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-python3-jwt-2.10.1-4ubuntu1.1.md) | May 28, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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