Bug 2544595

Summary:	CVE-2026-57585 python-msgpack: MessagePack for Python: Denial of Service via Unpacker reuse after error [fedora-all]
Product:	[Fedora] Fedora	Reporter:	Tomas Hoger <thoger>
Component:	python-msgpack	Assignee:	Jonathan Wright <jonathan>
Status:	NEW ---	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	high
Version:	rawhide	CC:	fschwarz, jonathan, kkeithley, ktdreyer, mail, pj.pandit
Target Milestone:	---	Keywords:	Security, SecurityTracking
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Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["49a30b0f-ca41-47e7-b653-d4dcde03b9a6"]}
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Bug Depends On:
Bug Blocks:	2496020

Description Tomas Hoger 2026-10-01 11:37:34 UTC

Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

MessagePack is the serializer implementation for Python msgpack.org. Prior to 1.2.1, there is an Out-of-bounds read/crash on Unpacker reuse after a caught error, potentially leading to a DoS attack.  If the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV. This issue has been fixed in version 1.2.1.

Comment 1 Felix Schwarz 2026-10-03 11:17:37 UTC

If you update msgpack to 1.2.3, please let us coordinate a borgbackup update. I guess I need to cherry-pick an upstream patch because there is no stable 1.4.6 release for borgbackup yet but at least for Fedora (all) + EPEL 10 it should be easy to apply.

For EL9 we use borgbackup 1.2.9 which requires msgpack == 1.1.1. EL8 bundles msgpack so I'll take care of that myself.