GitHub Advisoryadvisory · PyPI

GHSA-mq44-7p77-q5h7 AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate

MEDIUM Published 2026-08-03 Modified 2026-08-03 Official page ↗
Aliases
CVE-2026-59881
Ecosystem
PyPI
Packages
aiohttp
Severity
Moderate
CVSS 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
CWE-20
Reviewed
2026-08-03

Affected packages

• PyPI aiohttp: < 3.14.2 → fixed in 3.14.2

Description

Summary The client accepts and decompresses frames with the RSV1 bit set even when the `permessage-deflate` extension was not negotiated. Impact A client may unexpectedly decompress WebSocket frames when explicitly opted out. This could lead to additional CPU/memory consumption, but is unlikely to be a significant issue unless a zip bomb vulnerability or similar is also present. --- Patch: https://github.com/aio-libs/aiohttp/commit/47fb6ae354d4fa22048f4dbe7dbf82b625f0a2f6

Related

Alias · CVE (1)

  • CVE-2026-59881 AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. vulnerability

Weakness · CWE (1)

  • CWE-20 Improper Input Validation weakness

References