🛡️ CVE-2026-59881 — aiohttp

⚪ Unknown ✅ No Known Exploit CWE-20 NVD

N/A

CVSS Score

0 Low4 Medium7 High9 Critical10

Description

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

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

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. Rated impact: confidentiality none, integrity none, availability low.

Weakness class

CVE-2026-59881 is classified as CWE-20: Improper Input Validation. The application accepts input without checking that it has the expected form, so malformed values reach code that assumes they are well formed.

Affected software

CVE-2026-59881 is recorded against 2 packages.

aiohttp (fixed in 3.14.2)
unknown

Timeline and source

Published on 3 August 2026 and last revised on 4 August 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
github.com (Package)
github.com (Web)

Details

Severity Unknown

CVSS Score N/A

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

CWE CWE-20

Public Exploit ✅ No

Source NVD

Published 2026-08-03

Updated 2026-08-12

Modified 2026-08-04

Fix URL N/A

Affected Packages

Software	From version	Fixed in
aiohttp	—	3.14.2
unknown	—	—

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

🔗 NVD 🔗 Mitre

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