CVE-2026-26955

Description

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 structs 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.

Risk Information

Base Score

8.8

MODERATE

Vector

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

EPSS Score

Exploitation Probability

0.045

Associated Vulnerability

No records found

Patch Details

No records found

References

https://nvd.nist.gov/vuln/detail/CVE-2023-1234
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-1234