Amazon Linux 2023 : freerdp, freerdp-devel, freerdp-libs (ALAS2023-2026-1520)

critical Nessus Plugin ID 304610

Synopsis

The remote Amazon Linux 2023 host is missing a security update.

Description

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1520 advisory.

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, a client-side heap buffer overflow occurs in the FreeRDP client's AVC420/AVC444 YUV-to-RGB conversion path due to missing horizontal bounds validation of H.264 metablock regionRects coordinates. In yuv.c, the clamp() function (line 347) only validates top/bottom against the surface/YUV height, but never checks left/right against the surface width. When avc420_yuv_to_rgb (line 67) computes destination and source pointers using rect->left, it performs unchecked pointer arithmetic that can reach far beyond the allocated surface buffer. A malicious server sends a WIRE_TO_SURFACE_PDU_1 with AVC420 codec containing a regionRects entry where left greatly exceeds the surface width (e.g., left=60000 on a 128px surface). The H.264 bitstream decodes successfully, then yuv420_process_work_callback calls avc420_yuv_to_rgb which computes pDstPoint = pDstData + rect->top * nDstStep + rect->left * 4, writing 16-byte SSE vectors 1888+ bytes past the allocated heap region. This vulnerability is fixed in 3.24.0. (CVE-2026-29774)

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, a client-side heap out- of-bounds read/write occurs in FreeRDP's bitmap cache subsystem due to an off-by-one boundary check in bitmap_cache_put. A malicious server can send a CACHE_BITMAP_ORDER (Rev1) with cacheId equal to maxCells, bypassing the guard and accessing cells[] one element past the allocated array. This vulnerability is fixed in 3.24.0. (CVE-2026-29775)

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, Integer Underflow in update_read_cache_bitmap_order Function of FreeRDP's Core Library This vulnerability is fixed in 3.24.0.
(CVE-2026-29776)

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, a size_t underflow in the IMA-ADPCM and MS-ADPCM audio decoders leads to heap-buffer-overflow write via the RDPSND audio channel. In libfreerdp/codec/dsp.c, the IMA-ADPCM and MS-ADPCM decoders subtract block header sizes from a size_t variable without checking for underflow. When nBlockAlign (received from the server) is set such that size % block_size == 0 triggers the header parsing at a point where size is smaller than the header (4 or 8 bytes), the subtraction wraps size to ~SIZE_MAX. The while (size > 0) loop then continues for an astronomical number of iterations. This vulnerability is fixed in 3.24.0. (CVE-2026-31883)

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, division by zero in MS- ADPCM and IMA-ADPCM decoders when nBlockAlign is 0, leading to a crash. In libfreerdp/codec/dsp.c, both ADPCM decoders use size % block_size where block_size = context->common.format.nBlockAlign. The nBlockAlign value comes from the Server Audio Formats PDU on the RDPSND channel. The value 0 is not validated anywhere before reaching the decoder. When nBlockAlign = 0, the modulo operation causes a SIGFPE (floating point exception) crash. This vulnerability is fixed in 3.24.0. (CVE-2026-31884)

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, there is an out-of- bounds read in MS-ADPCM and IMA-ADPCM decoders due to unchecked predictor and step_index values from input data. This vulnerability is fixed in 3.24.0. (CVE-2026-31885)

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.24.0, there is an out-of- bounds read in freerdp_bitmap_decompress_planar when SrcSize is 0. The function dereferences *srcp (which points to pSrcData) without first verifying that SrcSize >= 1. When SrcSize is 0 and pSrcData is non-NULL, this reads one byte past the end of the source buffer. This vulnerability is fixed in 3.24.0.
(CVE-2026-31897)

Tenable has extracted the preceding description block directly from the tested product 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

Run 'dnf update freerdp --releasever 2023.10.20260330' or or 'dnf update --advisory ALAS2023-2026-1520 --releasever 2023.10.20260330' to update your system.

Plugin Details

Severity: Critical

ID: 304610

File Name: al2023_ALAS2023-2026-1520.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 4/1/2026

Updated: 4/1/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

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-2026-31883

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.8

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

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

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:freerdp-server-debuginfo, p-cpe:/a:amazon:linux:libwinpr, p-cpe:/a:amazon:linux:libwinpr-debuginfo, p-cpe:/a:amazon:linux:freerdp-libs-debuginfo, p-cpe:/a:amazon:linux:freerdp-server, p-cpe:/a:amazon:linux:freerdp-devel, p-cpe:/a:amazon:linux:libwinpr-devel, p-cpe:/a:amazon:linux:freerdp-debugsource, p-cpe:/a:amazon:linux:freerdp-libs, p-cpe:/a:amazon:linux:freerdp, p-cpe:/a:amazon:linux:freerdp-debuginfo, cpe:/o:amazon:linux:2023

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 4/1/2026

Vulnerability Publication Date: 3/13/2026

Reference Information

CVE: CVE-2026-29774, CVE-2026-29775, CVE-2026-29776, CVE-2026-31883, CVE-2026-31884, CVE-2026-31885, CVE-2026-31897

Detections

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