# CVE-2026-62995: joserfc: joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) stan...

CVE-2026-62995 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-62995, released July 31, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-62995
- Priority: Routine
- CVSS: n/a
- EPSS: 0.0015
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 29, 2026

## Description

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. in versions 1.7.1 and prior,  joserfc accepts JWTs with trailing padding (==) which are not conforming to the JOSE specifications. This leads to malleability of the JWTs when consumed by joserfc. Depending on this application this might or not be an issue. This could lead to bypass of token revocation or anti-replay protection when implemented as a deny list of tokens or a deny list of token hashes. Note that ECDSA JWS are always malleable because of the malleability of ECDSA signatures (first test case in the code bellow). This makes a scheme which assumes that JWTs are not malleable brittle. However for other signatures (or MAC) schemes it might make sense to assume non malleability of the token. This issue has been fixed in version 1.7.2.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | joserfc Debian 14 | 1.7.2-1 | [DEBIAN-CVE-2026-62995](https://patchblox.com/security/data/fix/linux/debian-cve-2026-62995.md) | Jul 31, 2026 |
| Linux | python-joserfc opensuse-leap 16.0 | 1.1.0-bp160.4.1 | [OPENSUSE-SU-2026:21515-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21515-1.md) | Jul 31, 2026 |

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Data as of 2026-11-09T01:18:40Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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