TencentOS Server 2: freerdp (TSSA-2026:0754)

high Nessus Plugin ID 329210

Synopsis

The remote TencentOS Server 2 host is missing one or more security updates.

Description

The version of Tencent Linux installed on the remote TencentOS Server 2 host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:0754 advisory.

Package updates are available for TencentOS Server 2 that fix the following vulnerabilities:

CVE-2026-26955:
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.

CVE-2026-26965:
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, in the RLE planar decode path, planar_decompress_plane_rle() writes into pDstData at ((nYDst+y) * nDstStep) + (4*nXDst) + nChannel without verifying that (nYDst+nSrcHeight) fits in the destination height or that (nXDst+nSrcWidth) fits in the destination stride. When TempFormat != DstFormat, pDstData becomes planar->pTempData (sized for the desktop), while nYDst is only validated against the **surface** by is_within_surface(). A malicious RDP server can exploit this to perform a heap out-of-bounds write with attacker-controlled offset and pixel data on any connecting FreeRDP client. The OOB write reaches up to 132,096 bytes past the temp buffer end, and on the brk heap (desktop 128128), an adjacent NSC_CONTEXT struct's decode function pointer is overwritten with attacker-controlled pixel data control-flowrelevant corruption (function pointer overwritten) demonstrated under deterministic heap layout (nsc->decode = 0xFF414141FF414141). Version 3.23.0 fixes the vulnerability.

Tenable has extracted the preceding description block directly from the Tencent Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Update the affected packages.

Plugin Details

Severity: High

ID: 329210

File Name: tencentos_TSSA_2026_0754.nasl

Version: 1.1

Type: Local

Family: Tencent Local Security Checks

Published: 7/23/2026

Updated: 7/23/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 57.62

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-26965

CVSS v3

Risk Factor: High

Base Score: 8.8

Temporal Score: 7.9

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:tencent:tencentos_server:2, p-cpe:/a:tencent:tencentos_server:freerdp

Required KB Items: Host/local_checks_enabled, Host/etc/os-release, Host/TencentOS/rpm-list, Host/cpu

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 4/9/2026

Vulnerability Publication Date: 2/25/2026

Reference Information

CVE: CVE-2026-26955, CVE-2026-26965

IAVA: 2026-A-0257-S

Detections

Analytics