Bug 2537695 - CVE-2026-84378 python-httpx2: HTTPX2: Denial of Service via crafted Server-Sent Events stream [fedora-all]
Summary: CVE-2026-84378 python-httpx2: HTTPX2: Denial of Service via crafted Server-Se...
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Fedora
Classification: Fedora
Component: python-httpx2
Version: rawhide
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: ---
Assignee: Ben Beasley
QA Contact:
URL:
Whiteboard: {"flaws": ["81e98e81-aeb4-4ea2-bc29-9...
Depends On:
Blocks: CVE-2026-84378
TreeView+ depends on / blocked
 
Reported: 2026-09-22 03:42 UTC by Ganesh
Modified: 2026-10-03 01:10 UTC (History)
3 users (show)

Fixed In Version: python-httpx2-2.13.1-1.fc44
Clone Of:
Environment:
Last Closed: 2026-10-03 01:10:09 UTC
Type: ---
Embargoed:


Attachments (Terms of Use)

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.


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