PT-2026-66548 · Aio Libs · Aiohttp

CVE-2026-59881 · Published 2026-07-30 · Updated 2026-07-30

Mitre

CVSS v4.0

6.9

Medium

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

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.

Fix

RCE

Weakness Enumeration

CWE-20

Related Identifiers

CVE-2026-59881

Affected Products

Aiohttp

References · 5

• https://nvd.nist.gov/vuln/detail/CVE-2026-59881 · Security Note
• https://github.com/aio-libs/aiohttp/security/advisories/GHSA-mq44-7p77-q5h7 · Note
• https://github.com/aio-libs/aiohttp/commit/47fb6ae354d4fa22048f4dbe7dbf82b625f0a2f6 · Note
• http://github.com/aio-libs/aiohttp/releases/tag/v3.14.2 · Note
• https://github.com/aio-libs/aiohttp/pull/12978 · Note