---
cve: "CVE-2026-40033"
severity: "HIGH"
cvss: 8.6
epss: "1.4%"
vendor: "FreeRDP"
kev: false
exploited: false
published: "2026-05-26 15:16:34"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-11-09T13:44:56+01:00"
---

# CVE-2026-40033

> 8.6 HIGH · 🧪 PoC

## Beschreibung

FreeRDP before 3.26.0 contains a heap-buffer-overflow vulnerability in gdi_CacheToSurface that allows remote attackers to write out-of-bounds heap memory. The vulnerability occurs because rectangle validation clamps coordinates to UINT16_MAX but performs copy operations using unclamped cache entry dimensions, enabling malicious RDP servers to trigger large out-of-bounds writes and potentially achieve remote code execution or client crash.

## CNA-Record (Kanon, cvelistV5)

- CNA: **VulnCheck**
- State: PUBLISHED
- Stand: 2026-07-27 12:05:46
- CNA-CVSS: **8.6** (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **poc**
  - Automatable: **no**
  - Technical Impact: **total**

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | 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.
- **CWE-122** — Heap-based Buffer Overflow
  The product writes past the end of a buffer that was allocated on the heap.

## Patch verfügbar (OSV)

- 3f6d7cb1f8973cc84c66b258a9a61c4e2b2f30a6 (Commit)
- d7508ebcd82842a691ae4941e5104d14240a89ae (Commit)

## BSI-Hinweise (deutsch)

- [FreeRDP: Mehrere Schwachstellen](https://wid.cert-bund.de/portal/wid/sicherheitshinweis/WID-SEC-W-2026-1470) — _BSI-Einstufung: hoch_
  Ein Angreifer kann mehrere Schwachstellen in FreeRDP ausnutzen, um beliebigen Programmcode auszuführen, einen Denial-of-Service-Zustand zu verursachen oder nicht näher spezifizierte Angriffe durchzuführen.

## Referenzen

- <https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-p6r2-4hgm-m6ff>
- <https://github.com/FreeRDP/FreeRDP/pull/12713>
- <https://github.com/FreeRDP/FreeRDP/commit/d7508ebcd82842a691ae4941e5104d14240a89ae>
- <https://www.vulncheck.com/advisories/freerdp-heap-buffer-overflow-in-gdi-cachetosurface-via-rectangle-validation-bypass>
- <https://access.redhat.com/errata/RHSA-2026:36203>
- <https://access.redhat.com/errata/RHSA-2026:46393>
- <https://access.redhat.com/security/cve/CVE-2026-40033>
- <https://bugzilla.redhat.com/show_bug.cgi?id=2481473>
- <https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40033.json>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/sicherheitsluecken/cve-2026-40033/) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_