Out-of-bounds write in Windows asyncio.ProacterEventLoop.sock_recvfrom_into() when using nbytes
Priority LOW 38CWE-787Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- Low · Low · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00392 33rd percentileScored 2026-11-07
Fix Fixed CPython (Python Software Foundation): 3.11.16, 3.12.14, 3.13.14 +2
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Python Software Foundation | CPython | before 3.11.16; 3.12.0 to before 3.12.14; 3.13.0 to before 3.13.14; 3.14.0a1 to before 3.14.5rc1; 3.15.0a1 to before 3.15.0b1 | 3.11.16, 3.12.14, 3.13.14, 3.14.5rc1, 3.15.0b1 | Patch available | CNA |
- CPython VendorPython Software Foundation Affected before 3.11.16; 3.12.0 to before 3.12.14; 3.13.0 to before 3.13.14; 3.14.0a1 to before 3.14.5rc1; 3.15.0a1 to before 3.15.0b1 Fixed in 3.11.16, 3.12.14, 3.13.14, 3.14.5rc1, 3.15.0b1 Patch available CNA
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:python:python:*:*:*:*:*:*:*:* | — | — | python-pillow |
- cpe:2.3:a:python:python:*:*:*:*:*:*:*:* Versions — — ·python-pillow
Remediation
- Fix · CNA CPython (Python Software Foundation) Fixed in 3.11.16, 3.12.14, 3.13.14, 3.14.5rc1, 3.15.0b1
Timeline
- 2026-10-02 Threatist record created from CVE-2026-3298
- 2026-10-03 Alias added: GHSA-3p9c-22jr-wq4x
References
Patch 6
- https://github.com/python/cpython/pull/148809
- https://github.com/python/cpython/commit/1274766d3c29007ab77245a72abbf8dce2a9db4d
- https://github.com/python/cpython/commit/27522b7d6e6588f03e61099dd858cd5a9314e2f2
- https://github.com/python/cpython/commit/95633d2aad4721e25e4dfd9f43dfb6e1edcbd741
- https://github.com/python/cpython/commit/6c8b85b3f1d83d5697ec19880960e1eacee56688
- https://github.com/python/cpython/commit/f5ca38739241fe7a40a4b116d5a8a1364dd6fea7
Advisory 1
More Python Software Foundation vulnerabilities
- TI-2024-07037 Quadratic complexity parsing cookies with backslashes CVSS 3.1HIGH 7.5
- TI-2024-11791 Bypass extraction filter to modify file metadata outside extraction directory CVSS 3.1MEDIUM 5.3
- TI-2024-00411 Quoted zip-bomb protection for zipfile CVSS 3.1MEDIUM 6.2
- TI-2026-13296 `HTTPPasswordMgr` can send saved HTTPS credentials via HTTP because of incorrect scheme matching CVSS 4.0MEDIUM 6.0
- TI-2024-06422 Email header injection due to unquoted newlines CVSS 3.1MEDIUM 5.5
- TI-2026-04606 Possible to hijack modules in current working directory CVSS 4.0MEDIUM 5.6
Sources
- CVE-2026-3298 · CVE Program
- CVE-2026-3298 · NVD
- FIRST EPSS
- GHSA-3p9c-22jr-wq4x · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences