CVE-2026-3298
Out-of-bounds write in Windows asyncio.ProacterEventLoop.sock_recvfrom_into() when using nbytes
At a glance
- Severity
- HIGH 8.8
- EPSS
- EPSS 0.39 % · percentile 33 (2026-10-27)
- State
- PUBLISHED
- Published
- Updated
- Assigner
- PSF
- NVD status
- Awaiting Analysis
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.
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | HIGH 8.8 | 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 | PSF |
| CVSS 4.0 | HIGH 8.8 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD · cna@python.org (Secondary) |
Weaknesses (CWE)
European references
- ENISA EUVD · EUVD-2026-24136
- GCVE · GCVE-0-2026-3298
CERT-FR advisories
- CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0556 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0474 — Vulnérabilité dans Python · cert.ssi.gouv.fr
Affected products
| Product | Versions |
|---|---|
| Python Software Foundation · CPython | affected 0 < 3.11.16 ; affected 3.12.0 < 3.12.14 ; affected 3.13.0 < 3.13.14 ; affected 3.14.0a1 < 3.14.5rc1 ; affected 3.15.0a1 < 3.15.0b1 |
References
- https://github.com/python/cpython/pull/148809
- https://github.com/python/cpython/issues/148808
- https://mail.python.org/archives/list/security-announce@python.org/thread/KWTPIQBOOOUNQP7UFSLBI437NJDFLA3F/
- 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
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |