CVE-2026-59881: aio-libs aiohttp · Improper Input Validation
Affects aio-libs aiohttpSource CVE Database V5
Not known to be exploited · CVSS 6.9 Medium : upgrade to 3.14.2 when convenient.
Data as of 29 Oct 2026, 07:15 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 3.14.2
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 30 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade aio-libs aiohttp to 3.14.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| aio-libsaiohttp | Affected
| Fixed in
|
PyPIaiohttppkg:pypi/aiohttpOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade aiohttp to version 3.14.2 or later, where this vulnerability is fixed. No other mitigation or temporary workaround is documented.
Description
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.
References
- github.com/aio-libs/aiohttp/security/advisories/GHSA-mq44-7p77-q5h7 (opens in a new tab)
- github.com/aio-libs/aiohttp/pull/12978 (opens in a new tab)
- github.com/aio-libs/aiohttp/commit/47fb6ae354d4fa22048f4dbe7dbf82b625f0a2f6 (opens in a new tab)
- github.com/aio-libs/aiohttp/releases/tag/v3.14.2 (opens in a new tab)