Bug 2547337

Summary:	CVE-2026-103262 python-flit: Tornado: Denial of Service via decompression bomb in CurlAsyncHTTPClient [fedora-all]
Product:	[Fedora] Fedora	Reporter:	jkelly <jkelly>
Component:	python-flit	Assignee:	Maxwell G <maxwell>
Status:	NEW ---	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	high
Version:	rawhide	CC:	epel-packagers-sig, maxwell, michel, python-packagers-sig
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["69f12751-9ff1-40bb-82ca-15e888c6361a"]}
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2544534

Description jkelly 2026-10-07 09:30:12 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.

Tornado versions before 6.5.9 contain an unbounded memory accumulation vulnerability in CurlAsyncHTTPClient that allows remote attackers to cause denial of service by sending a compressed response. Attackers can send a gzip-encoded decompression bomb that accumulates in memory without size limits, causing the application process to be killed by out-of-memory conditions.

Comment 1 Tomas Hoger 2026-10-09 19:04:31 UTC

This issue was filed because flit claims to bundle tornado via bundled() Provides:

Provides:       bundled(python3dist(tornado))

According to the .spec file comment, this was added because of single log.py file from the tornado project used in flit.  I think this bundled() Provides does more harm than benefit here.  If you want to avoid bugs opened in the future for torando CVEs, consider dropping that provide.