CVE-2026-3298 HIGH

CVE-2026-3298: Out-of-bounds write in Windows asyncio.ProacterEventLoop.sock_recvfrom_into() when using nbytes

Vendor Python Software Foundation
Product CPython
Weakness CWE-787
Published April 21, 2026
Last update June 10, 2026

CVSS base score

8.8/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

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

What the vulnerability does

01Description

The method "sock_recvfrom_into()" of "asyncio.ProacterEventLoop" (Windows only) was missing a boundary check for the data buffer when using nbytes parameter. This allowed for an out-of-bounds buffer write if data was larger than the buffer size. Non-Windows platforms are not affected.

Key dates

02Disclosure timeline

April 21, 2026 CVE published
June 10, 2026 Record updated