CVE-2025-68131

Name	CVE-2025-68131
Description	cbor2 provides encoding and decoding for the Concise Binary Object Representation (CBOR) serialization format. Starting in version 3.0.0 and prior to version 5.8.0, whhen a CBORDecoder instance is reused across multiple decode operations, values marked with the shareable tag (28) persist in memory and can be accessed by subsequent CBOR messages using the sharedref tag (29). This allows an attacker-controlled message to read data from previously decoded messages if the decoder is reused across trust boundaries. Version 5.8.0 patches the issue.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
cbor2 (PTS)	bullseye	5.2.0-4	vulnerable
	bookworm	5.4.6-1	vulnerable
	trixie	5.6.5-1	vulnerable
	forky, sid	5.7.1-1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
cbor2	source	(unstable)	(unfixed)	unimportant

Notes

https://github.com/agronholm/cbor2/security/advisories/GHSA-wcj4-jw5j-44wh
https://github.com/agronholm/cbor2/pull/268
Fixed by: https://github.com/agronholm/cbor2/commit/fb4ee1612a8a1ac0dbd8cf2f2f6f931a4e06d824 (5.8.0)
Debian builds src:cbor2 with CBOR2_BUILD_C_EXTENSION=0 (not building C extensions)