medium

CVE-2026-59881

PyPI · aiohttp

Summary

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

Severity
medium
EPSS
0.5% (p44)
CWE
CWE-20
Also known as
GHSA-mq44-7p77-q5h7
Published
2026-08-03
Updated
2026-08-03

Advisory details

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

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Sources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.