Bug 2509740

Summary: CVE-2026-59881 python-aiohttp: AIOHTTP: Denial of Service via unnegotiated WebSocket compression [epel-all]
Product: [Fedora] Fedora EPEL Reporter: Matteo Signorini <msignori>
Component: python-aiohttpAssignee: Jonathan Wright <jonathan>
Status: NEW --- QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: medium    
Version: epel10CC: code, igor.raits, jonathan, mail, python-packagers-sig
Target Milestone: ---Keywords: Security, SecurityTracking
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Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["cac533cf-6c94-4ac7-b5f3-b77dcc9d46c5"]}
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On:    
Bug Blocks: 2509545    

Description Matteo Signorini 2026-07-31 11:05:09 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.

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the WebSocket client accepts and decompresses frames with the RSV1 bit set even when the permessage-deflate extension was not negotiated, allowing a malicious server to cause unexpected CPU and memory consumption. This issue is fixed in version 3.14.2.
Comment 1 Ben Beasley 2026-07-31 13:01:29 UTC 
In EPEL10, this can’t be fixed by updating because several intervening “minor” releases contained documented breaking changes, including 3.14.0, https://github.com/aio-libs/aiohttp/releases#release-v3.14.0. Looking at https://www.cve.org/CVERecord?id=CVE-2026-59881, https://github.com/aio-libs/aiohttp/security/advisories/GHSA-mq44-7p77-q5h7, and the fix https://github.com/aio-libs/aiohttp/commit/47fb6ae354d4fa22048f4dbe7dbf82b625f0a2f6, it may be possible to backport the fix to at least EPEL10, which hasn’t diverged as severely as EPEL8 and EPEL9 have.

I’ve been updating this package lately via my python-packagers-sig group membership, but I wish someone else would take an interest in it. I will probably work on this CVE after a while, but it isn’t at the top of my list.