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Published: 14 July 2023

OpenIDC/cjose is a C library implementing the Javascript Object Signing and Encryption (JOSE). The AES GCM decryption routine incorrectly uses the Tag length from the actual Authentication Tag provided in the JWE. The spec says that a fixed length of 16 octets must be applied. Therefore this bug allows an attacker to provide a truncated Authentication Tag and to modify the JWE accordingly. Users should upgrade to a version >= Users unable to upgrade should avoid using AES GCM encryption and replace it with another encryption algorithm (e.g. AES CBC).



Cvss 3 Severity Score


Score breakdown


Package Release Status
Launchpad, Ubuntu, Debian
Released (0.6.0+dfsg1-1ubuntu0.1~esm1)
Available with Ubuntu Pro
Released (0.6.1+dfsg1-1ubuntu0.1)
Released (0.6.1+dfsg1-3ubuntu1.1)
kinetic Ignored
(end of life, was needed)
Released (
mantic Ignored
(end of life, was needs-triage)
noble Needs triage

trusty Ignored
(end of standard support)
upstream Needs triage

xenial Ignored
(end of standard support)

Severity score breakdown

Parameter Value
Base score 7.5
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact High
Availability impact None
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N