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Amazon Linux 2 : freerdp, --advisory ALAS2-2026-3221 (ALAS-2026-3221)

critical Nessus Plugin ID 304573

Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

The version of freerdp installed on the remote host is prior to 2.11.7-1. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2026-3221 advisory.

 FreeRDP is a free implementation of the Remote Desktop Protocol. Versions on the 2.x branch prior to to 2.11.8 and on the 3.x branch prior to 3.23.0 have an out-of-bounds read vulnerability in the FreeRDP client's RDPGFX channel that allows a malicious RDP server to read uninitialized heap memory by sending a crafted WIRE_TO_SURFACE_2 PDU with a `bitmapDataLength` value larger than the actual data in the packet.
 This can lead to information disclosure or client crashes when a user connects to a malicious server.
 Versions 2.11.8 and 3.23.0 fix the issue. (CVE-2026-25941)

 FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, `xf_rail_server_execute_result` indexes the global `error_code_names[]` array (7 elements, indices 0-6) with an unchecked `execResult->execResult` value received from the server, allowing an out-of-bounds read when the server sends an `execResult` value of 7 or greater. Version 3.23.0 fixes the issue.
 (CVE-2026-25942)

 FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, `xf_SetWindowMinMaxInfo` dereferences a freed `xfAppWindow` pointer because `xf_rail_get_window` in `xf_rail_server_min_max_info` returns an unprotected pointer from the `railWindows` hash table, and the main thread can concurrently delete the window (via a window delete order) while the RAIL channel thread is still using the pointer. Version 3.23.0 fixes the issue. (CVE-2026-25952)

 FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, `xf_AppUpdateWindowFromSurface` reads from a freed `xfAppWindow` because the RDPGFX DVC thread obtains a bare pointer via `xf_rail_get_window` without any lifetime protection, while the main thread can concurrently delete the window through a fastpath window-delete order. Version 3.23.0 fixes the issue.
 (CVE-2026-25953)

 FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, `xf_rail_server_local_move_size` dereferences a freed `xfAppWindow` pointer because `xf_rail_get_window` returns an unprotected pointer from the `railWindows` hash table, and the main thread can concurrently delete the window (via a window delete order) while the RAIL channel thread is still using the pointer.
 Version 3.23.0 fixes the issue. (CVE-2026-25954)

 FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, `xf_clipboard_format_equal` reads freed `lastSentFormats` memory because `xf_clipboard_formats_free` (called from the cliprdr channel thread during auto-reconnect) frees the array while the X11 event thread concurrently iterates it in `xf_clipboard_changed`, triggering a heap use after free. Version 3.23.0 fixes the issue. (CVE-2026-25997)

 FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, a buffer overread in `freerdp_image_copy_from_icon_data()` (libfreerdp/codec/color.c) can be triggered by crafted RDP Window Icon (TS_ICON_INFO) data. The bug is reachable over the network when a client processes icon data from an RDP server (or from a man-in-the-middle). Version 3.23.0 fixes the issue. (CVE-2026-26271)

 FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, `rail_window_free` dereferences a freed `xfAppWindow` pointer during `HashTable_Free` cleanup because `xf_rail_window_common` calls `free(appWindow)` on title allocation failure without first removing the entry from the `railWindows` hash table, leaving a dangling pointer that is freed again on disconnect.
 Version 3.23.0 fixes the vulnerability. (CVE-2026-26986)

 FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, a missing bounds check in `smartcard_unpack_read_size_align()` (`libfreerdp/utils/smartcard_pack.c:1703`) allows a malicious RDP server to crash the FreeRDP client via a reachable `WINPR_ASSERT` - `abort()`. The crash occurs in upstream builds where `WITH_VERBOSE_WINPR_ASSERT=ON` (default in FreeRDP 3.22.0 / current WinPR CMake defaults). Smartcard redirection must be explicitly enabled by the user (e.g., `xfreerdp /smartcard`; `/smartcard-logon` implies `/smartcard`). Version 3.23.0 fixes the issue. (CVE-2026-27015)

 FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, the function `Stream_EnsureCapacity` can create an endless blocking loop. This may affect all client and server implementations using `FreeRDP`. For practical exploitation this will only work on 32bit systems where the available physical memory is `>= SIZE_MAX`. Version 3.23.0 contains a patch. No known workarounds are available. (CVE-2026-27951)

 A flaw was found in FreeRDP, a free implementation of the Remote Desktop Protocol (RDP). The `gdi_surface_bits()` function, which processes `SURFACE_BITS_COMMAND` messages, does not properly validate image dimensions (`bmp.width` and `bmp.height`) provided by a malicious RDP server. This can lead to a heap buffer overflow during bitmap decoding and memory operations. A remote attacker could exploit this to overwrite adjacent memory, potentially resulting in arbitrary code execution. (CVE-2026-31806)

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 'yum update freerdp' or or 'yum update --advisory ALAS2-2026-3221' to update your system.

See Also

https://alas.aws.amazon.com//AL2/ALAS2-2026-3221.html

https://alas.aws.amazon.com/faqs.html

https://explore.alas.aws.amazon.com/CVE-2026-25941.html

https://explore.alas.aws.amazon.com/CVE-2026-25942.html

https://explore.alas.aws.amazon.com/CVE-2026-25952.html

https://explore.alas.aws.amazon.com/CVE-2026-25953.html

https://explore.alas.aws.amazon.com/CVE-2026-25954.html

https://explore.alas.aws.amazon.com/CVE-2026-25997.html

https://explore.alas.aws.amazon.com/CVE-2026-26271.html

https://explore.alas.aws.amazon.com/CVE-2026-26986.html

https://explore.alas.aws.amazon.com/CVE-2026-27015.html

https://explore.alas.aws.amazon.com/CVE-2026-27951.html

https://explore.alas.aws.amazon.com/CVE-2026-31806.html

Plugin Details

Severity: Critical

ID: 304573

File Name: al2_ALAS-2026-3221.nasl

Version: 1.1

Type: Local

Agent: unix

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-2026-31806

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

CVSS v4

Risk Factor: Critical

Base Score: 9.3

Threat Score: 8.9

Threat Vector: CVSS:4.0/E:P

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

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:libwinpr, p-cpe:/a:amazon:linux:freerdp-devel, p-cpe:/a:amazon:linux:libwinpr-devel, cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:freerdp-libs, p-cpe:/a:amazon:linux:freerdp, p-cpe:/a:amazon:linux:freerdp-debuginfo

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: 2/25/2026

Reference Information

CVE: CVE-2026-25941, CVE-2026-25942, CVE-2026-25952, CVE-2026-25953, CVE-2026-25954, CVE-2026-25997, CVE-2026-26271, CVE-2026-26986, CVE-2026-27015, CVE-2026-27951, CVE-2026-31806

IAVA: 2026-A-0257