CVE-2026-62995

Aliases:UBUNTU-CVE-2026-62995DEBIAN-CVE-2026-62995openSUSE-SU-2026:11423-1openSUSE-SU-2026:21515-1
Advisory lineage Upstream: 0 Downstream: 1
Downstream
RHSA-2026:48758
Deferred
Published: 29 Jul 2026, 18:27
Last modified:30 Jul 2026, 14:32

Vulnerability Summary

Overall Risk (default)
minimal
9/100
CVSS Score
2.3 LOW
v4.0 (cve.org)
EPSS Score
0.11% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

29 Jul 2026, 18:27
Published
Vulnerability first disclosed
30 Jul 2026, 14:32
Last Modified
Vulnerability information updated

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.

CVSS Metrics

  • v4.0•LOW•Score: 2.3CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
  • v4.0•LOW•Score: 2.3CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Trends

Current EPSS score: 0.11%• Percentile: 1%

Techniques & Countermeasures

  • CWE-345•Insufficient Verification of Data Authenticity

    The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.

Affected Systems

  • authlib•joserfc

    < 1.7.2

  • debian•joserfc

    all | < 1.7.2-1

  • ubuntu•joserfc

    all

  • opensuse•python-joserfc&distro=openSUSE Leap 16.0

    < 1.1.0-bp160.4.1

  • opensuse•python-joserfc&distro=openSUSE Tumbleweed

    < 1.7.4-2.1

References (6)