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 systems. The method does not properly validate the size of the data buffer against the nbytes parameter, allowing data larger than the buffer to overwrite memory beyond its boundary. This is classified under CWE-787 (Out-of-bounds Write). The flaw affects CPython versions 3.11.0, 3.14.0a1, 3.15.0a1, 3.14.0, and 3.15.0. The CVSS 4.0 base score is 8.8, indicating high severity with network attack vector, low attack complexity, no privileges or user interaction required, and high impact on availability.
Potential Impact
Successful exploitation of this vulnerability can result in memory corruption due to out-of-bounds writes, potentially leading to application crashes or arbitrary code execution. The vulnerability affects only Windows platforms running the specified CPython versions. Non-Windows platforms are not impacted. There are no known exploits in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the Python Software Foundation advisory for current remediation guidance. No official fix or temporary workaround has been documented at this time. Users running affected CPython versions on Windows should monitor vendor communications for patches and avoid using the vulnerable method if possible until a fix is 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
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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 systems. The method does not properly validate the size of the data buffer against the nbytes parameter, allowing data larger than the buffer to overwrite memory beyond its boundary. This is classified under CWE-787 (Out-of-bounds Write). The flaw affects CPython versions 3.11.0, 3.14.0a1, 3.15.0a1, 3.14.0, and 3.15.0. The CVSS 4.0 base score is 8.8, indicating high severity with network attack vector, low attack complexity, no privileges or user interaction required, and high impact on availability.
Potential Impact
Successful exploitation of this vulnerability can result in memory corruption due to out-of-bounds writes, potentially leading to application crashes or arbitrary code execution. The vulnerability affects only Windows platforms running the specified CPython versions. Non-Windows platforms are not impacted. There are no known exploits in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the Python Software Foundation advisory for current remediation guidance. No official fix or temporary workaround has been documented at this time. Users running affected CPython versions on Windows should monitor vendor communications for patches and avoid using the vulnerable method if possible until a fix is 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
- Remediation Level
- null
Threat ID: 69e7913319fe3cd2cddd4302
Added to database: 04/21/2026, 15:01:07 UTC
Last enriched: 07/06/2026, 23:31:05 UTC
Last updated: 07/31/2026, 19:30:03 UTC
Views: 775
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