---
cve: "CVE-2026-26955"
severity: "HIGH"
cvss: 8.8
epss: "54%"
vendor: "FreeRDP"
kev: false
exploited: false
published: "2026-02-25 21:16:42"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-07T07:49:21+02:00"
---

# CVE-2026-26955

> 8.8 HIGH · 🧪 PoC

## Beschreibung

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, a malicious RDP server can trigger a heap buffer overflow in FreeRDP clients using the GDI surface pipeline (e.g., `xfreerdp`) by sending an RDPGFX ClearCodec surface command with an out-of-bounds destination rectangle. The `gdi_SurfaceCommand_ClearCodec()` handler does not call `is_within_surface()` to validate the command rectangle against the destination surface dimensions, allowing attacker-controlled `cmd->left`/`cmd->top` (and subcodec rectangle offsets) to reach image copy routines that write into `surface->data` without bounds enforcement. The OOB write corrupts an adjacent `gdiGfxSurface` struct's `codecs*` pointer with attacker-controlled pixel data, and corruption of `codecs*` is sufficient to reach an indirect function pointer call (`NSC_CONTEXT.decode` at `nsc.c:500`) on a subsequent codec command — full instruction pointer (RIP) control demonstrated in exploitability harness. Users should upgrade to version 3.23.0 to receive a patch.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Erforderlich | good |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- b933ae18d9ad2a1d73c610868fcc30eb61654070 (Commit)
- 7d8fdce2d0ef337cb86cb37fc0c436c905e04d77 (Commit)

## Referenzen

- <https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-mr6w-ch7c-mqqj>
- <https://github.com/FreeRDP/FreeRDP/commit/7d8fdce2d0ef337cb86cb37fc0c436c905e04d77>
- <https://access.redhat.com/errata/RHSA-2026:19033>
- <https://access.redhat.com/errata/RHSA-2026:5936>
- <https://access.redhat.com/errata/RHSA-2026:5939>
- <https://access.redhat.com/errata/RHSA-2026:6004>
- <https://access.redhat.com/errata/RHSA-2026:6005>
- <https://access.redhat.com/errata/RHSA-2026:6384>
- <https://access.redhat.com/errata/RHSA-2026:6385>
- <https://access.redhat.com/errata/RHSA-2026:6395>
- <https://access.redhat.com/errata/RHSA-2026:6396>
- <https://access.redhat.com/errata/RHSA-2026:6616>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-26955) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_