AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate
PYSEC-2026-3547 · CVE-2026-59881 · GHSA-mq44-7p77-q5h7
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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
References
- WEB https://github.com/aio-libs/aiohttp/security/advisories/GHSA-mq44-7p77-q5h7
- ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-59881
- WEB https://github.com/aio-libs/aiohttp/pull/12978
- WEB https://github.com/aio-libs/aiohttp/commit/47fb6ae354d4fa22048f4dbe7dbf82b625f0a2f6
- PACKAGE https://github.com/aio-libs/aiohttp
- WEB http://github.com/aio-libs/aiohttp/releases/tag/v3.14.2
- PACKAGE https://pypi.org/project/aiohttp
- ADVISORY https://github.com/advisories/GHSA-mq44-7p77-q5h7
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