Bug 2544592

Summary:	CVE-2026-57585 borgbackup: MessagePack for Python: Denial of Service via Unpacker reuse after error [epel-all]
Product:	[Fedora] Fedora EPEL	Reporter:	Tomas Hoger <thoger>
Component:	borgbackup	Assignee:	Felix Schwarz <fschwarz>
Status:	ASSIGNED ---	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	high
Version:	epel8	CC:	fschwarz
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["49a30b0f-ca41-47e7-b653-d4dcde03b9a6"]}
Fixed In Version:		Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2496020

Description Tomas Hoger 2026-10-01 11:36:59 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 11:20:19 UTC

This issue should be about EPEL 8 which bundles an older version of msgpack.

EPEL 9+10 use whatever msgpack is provided by the system (though we need to patch borgbackup to accept the latest msgpack 1.2.3).

Upstream support for msgpack 1.2.3 in borgbackup 1.4.x: https://github.com/borgbackup/borg/commit/084f3fbce66c29334ad0a1d83324011398339547