---
cve: "CVE-2026-3298"
severity: "HIGH"
cvss: 8.8
epss: "0.4%"
vendor: "Python Software Foundation"
kev: false
exploited: false
published: "2026-04-21 15:16:37"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-11-02T15:51:36+01:00"
---

# CVE-2026-3298

> 8.8 HIGH · 🧪 PoC

## Beschreibung

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.

## CNA-Record (Kanon, cvelistV5)

- CNA: **PSF**
- State: PUBLISHED
- Stand: 2026-08-13 00:27:55
- CNA-CVSS: **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`)

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **no**
  - Technical Impact: **partial**

## CVSS-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Schwachstellen-Klasse

- **CWE-787** — Out-of-bounds Write
  The product writes data past the end, or before the beginning, of the intended buffer.

## Patch verfügbar (OSV)

- 41388c9cb160d0886d5ca00d2e6c8782608a4549 (Commit)
- 2abcf904b8dac8c999d2b3aac76681abb333798a (Commit)

## BSI-Hinweise (deutsch)

- [CPython: Schwachstelle ermöglicht nicht spezifizierten Angriff](https://wid.cert-bund.de/portal/wid/sicherheitshinweis/WID-SEC-W-2026-1222) — _BSI-Einstufung: hoch_
  Ein entfernter, anonymer Angreifer kann eine Schwachstelle in CPython ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen.

## Referenzen

- <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>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/sicherheitsluecken/cve-2026-3298/) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_