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VulnerabilityPublished

CVE-2026-59881: aio-libs aiohttp · Improper Input Validation

Affects aio-libs aiohttpSource CVE Database V5

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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

CVSS 4.0 base score
6.9Medium
How severe the flaw is on the 0–10 CVSS scale.
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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 30 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
aio-libsaiohttpAffected
  • <3.14.2
Fixed in
  • 3.14.2
PyPIaiohttppkg:pypi/aiohttpOther threatsAffected
  • <3.14.2
Fixed in
  • 3.14.2

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

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