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CVE-2026-3298VulnerabilityPublished Updated

Windows asyncio.ProacterEventLoop.sock_recvfrom_into() · Out-of-bounds Write

Affects MicrosoftSource GCVE Database

0
Authoritative record:CVE-2026-3298· High 8.8

Not known to be exploited · CVSS 8.8 High · fixed in 3.15.0b1 : patch Microsoft soon.

Data as of 27 Oct 2026, 00:12 UTC

CVSS 4.0 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 3.15.0b1, 3.14.5rc1, 3.13.14 +2
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 21 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Python Software FoundationCPythonAffected
  • >=3.15.0a1 <3.15.0b1
Fixed in
  • 3.15.0b1
Python Software FoundationCPythonAffected
  • >=3.14.0a1 <3.14.5rc1
Fixed in
  • 3.14.5rc1
Python Software FoundationCPythonAffected
  • >=3.13.0 <3.13.14
Fixed in
  • 3.13.14
Python Software FoundationCPythonAffected
  • >=3.12.0 <3.12.14
Fixed in
  • 3.12.14
Python Software FoundationCPythonAffected
  • <3.11.16
Fixed in
  • 3.11.16
PyPIcpythonpkg:pypi/cpythonOther threatsAffected
  • =3.11.0
  • =3.14.0
  • =3.15.0
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

An out-of-bounds write vulnerability exists in Windows asyncio.ProactorEventLoop.sock_recvfrom_into() when using the nbytes parameter. This flaw could potentially lead to memory corruption due to improper handling of buffer sizes.

References

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