CVE-2026-62995
CVE-2026-62995 · joserfc accepts JWT with padding, leading to JWT malleability
This page contains facts from public vulnerability sources. Check the original advisory before updating.
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.
CVSS 2.3 · Low · EPSS 0.1% · Fix available
- Published
- Updated
Stack: system
Affected products and versions
joserfc
- Versions
- < 1.7.2: Affected
No fix published
joserfc Debian:13
- Versions
- 1.1.0-1
- 1.2.0-1
- 1.2.2-1
- 1.3.1-1
- 1.3.2-1
- 1.3.4-1
- 1.4.0-1
- 1.4.1-1
- 1.4.3-1
- 1.5.0-1
- 1.6.0-1
- 1.6.1-1
- 1.6.2-1
- 1.6.3-1
- 1.6.4-1
- 1.6.5-1
- 1.6.8-1
- 1.7.0-1
- 1.7.1-1
- 1.7.2-1
- 1.7.3-1
- 1.7.4-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published
joserfc Debian:14
- Versions
- 1.1.0-1
- 1.2.0-1
- 1.2.2-1
- 1.3.1-1
- 1.3.2-1
- 1.3.4-1
- 1.4.0-1
- 1.4.1-1
- 1.4.3-1
- 1.5.0-1
- 1.6.0-1
- 1.6.1-1
- 1.6.2-1
- 1.6.3-1
- 1.6.4-1
- 1.6.5-1
- 1.6.8-1
- 1.7.0-1
- 1.7.1-1
- Affected ranges
- ECOSYSTEM: < 1.7.2-1
Update to 1.7.2-1
joserfc Ubuntu:26.04:LTS
- Versions
- 1.2.2-1
- 1.4.0-1
- 1.4.1-1
- 1.4.3-1
- 1.5.0-1
- 1.6.2-1
- Affected ranges
- ECOSYSTEM: (−∞, +∞)
No fix published