# CVE-2026-75509: joserfc: joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) stan...

CVE-2026-75509 is fixed in joserfc on 1 platform by DEBIAN-CVE-2026-75509 (version 1.7.3-1), released August 26, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-75509
- Priority: Routine
- CVSS: 6.5 (medium)
- EPSS: 0.0012
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 24, 2026

## Description

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to version 1.7.3, JWTClaimsRegistry applies membership matching to list-valued iss and sub claims, allowing an array-valued iss that contains the expected issuer to pass an intended equality check and enabling issuer-validation bypass. This issue is fixed in version 1.7.3.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | joserfc Debian 14 | 1.7.3-1 | [DEBIAN-CVE-2026-75509](https://patchblox.com/security/data/fix/linux/debian-cve-2026-75509.md) | Aug 26, 2026 |

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Data as of 2026-11-08T19:12:23Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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