CVE-2026-59881

AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate

Published Jul 30, 2026 CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4876-1 python-aiohttp security update
Github GHSA Github GHSA GHSA-mq44-7p77-q5h7 AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate
History
Type Values Removed Values Added
First Time appeared Aio-libs
Aio-libs aiohttp
Vendors & Products Aio-libs
Aio-libs aiohttp
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Title AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate
Weaknesses CWE-20
References
Metrics cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jul 30, 2026, 6:35 PM
Reserved
Jul 7, 2026, 4:40 PM
Status
Deferred
Published
Jul 30, 2026, 7:18 PM
Modified
Oct 23, 2026, 10:10 PM