CVE-2026-3298: CWE-787 Out-of-bounds write in Python Software Foundation CPython
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.
AI Analysis
Technical Summary
The vulnerability CVE-2026-3298 involves an out-of-bounds write in the sock_recvfrom_into() method of asyncio.ProactorEventLoop on Windows platforms in CPython. The method fails to properly check the boundary of the data buffer when the nbytes parameter is used, allowing data larger than the buffer to overwrite adjacent memory. This can lead to memory corruption and potentially arbitrary code execution or application instability. The issue affects multiple CPython versions as explicitly listed. No remediation or patch has been confirmed at this time.
Potential Impact
Successful exploitation of this vulnerability could result in memory corruption due to out-of-bounds writes, which may lead to application crashes or potentially arbitrary code execution. The impact is limited to Windows platforms running affected CPython versions. Non-Windows platforms are not affected.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, users should consider avoiding the use of asyncio.ProactorEventLoop's sock_recvfrom_into() method with untrusted data on Windows or apply other protective measures as recommended by the Python Software Foundation once available.
CVE-2026-3298: CWE-787 Out-of-bounds write in Python Software Foundation CPython
Description
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.
CVSS v4.0
Score 8.8high
Affected software
Python Software Foundation
CPython
pkg:github/CPythonRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability CVE-2026-3298 involves an out-of-bounds write in the sock_recvfrom_into() method of asyncio.ProactorEventLoop on Windows platforms in CPython. The method fails to properly check the boundary of the data buffer when the nbytes parameter is used, allowing data larger than the buffer to overwrite adjacent memory. This can lead to memory corruption and potentially arbitrary code execution or application instability. The issue affects multiple CPython versions as explicitly listed. No remediation or patch has been confirmed at this time.
Potential Impact
Successful exploitation of this vulnerability could result in memory corruption due to out-of-bounds writes, which may lead to application crashes or potentially arbitrary code execution. The impact is limited to Windows platforms running affected CPython versions. Non-Windows platforms are not affected.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, users should consider avoiding the use of asyncio.ProactorEventLoop's sock_recvfrom_into() method with untrusted data on Windows or apply other protective measures as recommended by the Python Software Foundation once available.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- PSF
- Date Reserved
- 2026-02-26T20:12:47.041Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 69e7913319fe3cd2cddd4302
Added to database: 04/21/2026, 15:01:07 UTC
Last enriched: 08/15/2026, 14:42:08 UTC
Last updated: 09/14/2026, 22:01:33 UTC
Views: 843
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