Bug 2560130

Summary:	CVE-2026-115349 python-mistune: mistune: Denial of Service via deeply nested square brackets [fedora-44]
Product:	[Fedora] Fedora	Reporter:	Ronit Dey <rdey>
Component:	python-mistune	Assignee:	Miro Hrončok <mhroncok>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	high
Version:	44	CC:	epel-packagers-sig, mhroncok, neil, python-packagers-sig, romain.geissler
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["60da071e-058c-4be0-88e2-6c567f2fef3e"]}
Fixed In Version:	python-mistune-3.3.4-1.fc44	Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2026-11-06 01:26:29 UTC	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:	2559278

Description Ronit Dey 2026-10-23 17:47:37 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.

Mistune from 3.0.0 before 3.3.0 contains an algorithmic complexity denial of service vulnerability in the parse_link_text function in src/mistune/helpers.py. Attackers can submit markdown with deeply nested square brackets triggering quadratic parsing time, exhausting server CPU with small crafted requests.

Comment 1 Fedora Update System 2026-10-28 12:01:50 UTC

FEDORA-2026-ea39a303cf (python-mistune-3.3.4-1.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-ea39a303cf

Comment 2 Fedora Update System 2026-10-29 02:47:26 UTC

FEDORA-2026-ea39a303cf has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-ea39a303cf`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-ea39a303cf

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 3 Fedora Update System 2026-11-06 01:26:29 UTC

FEDORA-2026-ea39a303cf (python-mistune-3.3.4-1.fc44) has been pushed to the Fedora 44 stable repository.
If problem still persists, please make note of it in this bug report.