Bug 2537695

Summary:	CVE-2026-84378 python-httpx2: HTTPX2: Denial of Service via crafted Server-Sent Events stream [fedora-all]
Product:	[Fedora] Fedora	Reporter:	Ganesh <gnaik>
Component:	python-httpx2	Assignee:	Ben Beasley <code>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	rawhide	CC:	carlwgeorge, code, python-packagers-sig
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["81e98e81-aeb4-4ea2-bc29-9a4b4b3ac4d0"]}
Fixed In Version:	python-httpx2-2.13.1-1.fc44	Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2026-10-03 01:10:09 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:	2527694

Description Ganesh 2026-09-22 03:42:28 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.

HTTPX2 is a next generation HTTP client for Python. From 2.5.0 until 2.10.0, the HTTPX2 Server-Sent Events parser in src/httpx2/httpx2/_sse.py repeatedly copies and rescans buffered text in _SSELineDecoder.decode() when an attacker-controlled or compromised SSE endpoint splits one unterminated line across many response chunks. The behavior affects httpx2.Client.sse() and httpx2.AsyncClient.sse(), and the total processing work grows quadratically with the line length, allowing a crafted stream to consume excessive CPU and block a synchronous worker or asynchronous event loop. This issue is fixed in version 2.10.0.

Comment 1 Ben Beasley 2026-09-22 05:39:23 UTC

Fedora 45+ already have a recent enough version of python-httpx2. Fedora 44 has an older version for dependency reasons, particularly click, but it appears that upstream’s lower bound is overly conservative and can be loosened, allowing the package to be updated.

Comment 2 Fedora Update System 2026-09-22 06:21:13 UTC

FEDORA-2026-a69588e2cd (python-httpx2-2.13.0-2.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-a69588e2cd

Comment 3 Fedora Update System 2026-09-23 01:58:46 UTC

FEDORA-2026-a69588e2cd 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-a69588e2cd`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-a69588e2cd

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

Comment 4 Fedora Update System 2026-09-24 01:54:56 UTC

FEDORA-2026-a69588e2cd 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-a69588e2cd`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-a69588e2cd

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

Comment 5 Fedora Update System 2026-10-03 01:10:09 UTC

FEDORA-2026-a69588e2cd (python-httpx2-2.13.1-1.fc44) has been pushed to the Fedora 44 stable repository.
If problem still persists, please make note of it in this bug report.