CVE-2026-3298: CWE-787 Out-of-bounds write in Python Software Foundation CPython
CVE-2026-3298 is a high-severity vulnerability in the Python Software Foundation's CPython 3. 11. 0 on Windows platforms. The asyncio. ProactorEventLoop method sock_recvfrom_into() lacks proper boundary checks on the data buffer when using the nbytes parameter, leading to an out-of-bounds write if incoming data exceeds the buffer size. This issue is specific to Windows and does not affect non-Windows platforms. No official patch or remediation guidance is currently available from the vendor. There are no known exploits in the wild at this time.
AI Analysis
Technical Summary
The vulnerability CVE-2026-3298 affects CPython version 3.11.0 on Windows only. The method sock_recvfrom_into() in asyncio.ProactorEventLoop fails to validate the size of the data buffer against the nbytes parameter, allowing an attacker to cause an out-of-bounds write when the received data is larger than the buffer. This is classified as a CWE-787 (Out-of-bounds Write) vulnerability. The CVSS 4.0 score is 8.8, indicating high severity with network attack vector, no privileges or user interaction required, and high impact on availability. No patch or official remediation level has been published by the Python Software Foundation as of the data provided.
Potential Impact
Successful exploitation of this vulnerability could lead to memory corruption due to out-of-bounds writes, potentially causing application crashes or other unpredictable behavior. The CVSS score indicates a high impact on availability and a low impact on confidentiality and integrity. The vulnerability is exploitable remotely without authentication or user interaction on affected Windows systems running CPython 3.11.0. Non-Windows platforms are not affected.
Mitigation Recommendations
Patch status is not yet confirmed — check the Python Software Foundation advisory for current remediation guidance. Until an official fix is released, users should consider avoiding use of asyncio.ProactorEventLoop's sock_recvfrom_into() method with untrusted data on Windows or apply other application-level mitigations to limit exposure. Monitor official Python channels for updates.
CVE-2026-3298: CWE-787 Out-of-bounds write in Python Software Foundation CPython
Description
CVE-2026-3298 is a high-severity vulnerability in the Python Software Foundation's CPython 3. 11. 0 on Windows platforms. The asyncio. ProactorEventLoop method sock_recvfrom_into() lacks proper boundary checks on the data buffer when using the nbytes parameter, leading to an out-of-bounds write if incoming data exceeds the buffer size. This issue is specific to Windows and does not affect non-Windows platforms. No official patch or remediation guidance is currently available from the vendor. There are no known exploits in the wild at this time.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability CVE-2026-3298 affects CPython version 3.11.0 on Windows only. The method sock_recvfrom_into() in asyncio.ProactorEventLoop fails to validate the size of the data buffer against the nbytes parameter, allowing an attacker to cause an out-of-bounds write when the received data is larger than the buffer. This is classified as a CWE-787 (Out-of-bounds Write) vulnerability. The CVSS 4.0 score is 8.8, indicating high severity with network attack vector, no privileges or user interaction required, and high impact on availability. No patch or official remediation level has been published by the Python Software Foundation as of the data provided.
Potential Impact
Successful exploitation of this vulnerability could lead to memory corruption due to out-of-bounds writes, potentially causing application crashes or other unpredictable behavior. The CVSS score indicates a high impact on availability and a low impact on confidentiality and integrity. The vulnerability is exploitable remotely without authentication or user interaction on affected Windows systems running CPython 3.11.0. Non-Windows platforms are not affected.
Mitigation Recommendations
Patch status is not yet confirmed — check the Python Software Foundation advisory for current remediation guidance. Until an official fix is released, users should consider avoiding use of asyncio.ProactorEventLoop's sock_recvfrom_into() method with untrusted data on Windows or apply other application-level mitigations to limit exposure. Monitor official Python channels for updates.
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: 4/21/2026, 3:01:07 PM
Last enriched: 4/21/2026, 3:16:05 PM
Last updated: 4/21/2026, 4:13:07 PM
Views: 5
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.