Amazon Linux 2 : xorg-x11-server (ALAS-2025-2791)

high Nessus Plugin ID 233377

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Synopsis

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

Description

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2025-2791 advisory.

A use-after-free flaw was found in X.Org and Xwayland. The root cursor is referenced in the X server as a global variable. If a client frees the root cursor, the internal reference points to freed memory and causes a use-after-free. (CVE-2025-26594)

A buffer overflow flaw was found in X.Org and Xwayland. The code in XkbVModMaskText() allocates a fixed- sized buffer on the stack and copies the names of the virtual modifiers to that buffer. The code fails to check the bounds of the buffer and would copy the data regardless of the size. (CVE-2025-26595)

A heap overflow flaw was found in X.Org and Xwayland. The computation of the length in XkbSizeKeySyms() differs from what is written in XkbWriteKeySyms(), which may lead to a heap-based buffer overflow.
(CVE-2025-26596)

A buffer overflow flaw was found in X.Org and Xwayland. If XkbChangeTypesOfKey() is called with a 0 group, it will resize the key symbols table to 0 but leave the key actions unchanged. If the same function is later called with a non-zero value of groups, this will cause a buffer overflow because the key actions are of the wrong size. (CVE-2025-26597)

An out-of-bounds write flaw was found in X.Org and Xwayland. The function GetBarrierDevice() searches for the pointer device based on its device ID and returns the matching value, or supposedly NULL, if no match was found. However, the code will return the last element of the list if no matching device ID is found, which can lead to out-of-bounds memory access. (CVE-2025-26598)

An access to an uninitialized pointer flaw was found in X.Org and Xwayland. The function compCheckRedirect() may fail if it cannot allocate the backing pixmap. In that case, compRedirectWindow() will return a BadAlloc error without validating the window tree marked just before, which leaves the validated data partly initialized and the use of an uninitialized pointer later. (CVE-2025-26599)

A use-after-free flaw was found in X.Org and Xwayland. When a device is removed while still frozen, the events queued for that device remain while the device is freed. Replaying the events will cause a use- after-free. (CVE-2025-26600)

A use-after-free flaw was found in X.Org and Xwayland. When changing an alarm, the values of the change mask are evaluated one after the other, changing the trigger values as requested, and eventually, SyncInitTrigger() is called. If one of the changes triggers an error, the function will return early, not adding the new sync object, possibly causing a use-after-free when the alarm eventually triggers.
(CVE-2025-26601)

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 xorg-x11-server' to update your system.

Plugin Details

Severity: High

ID: 233377

File Name: al2_ALAS-2025-2791.nasl

Version: 1.1

Type: local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 3/27/2025

Updated: 3/27/2025

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

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

CVSS Score Source: CVE-2025-26601

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

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

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

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:xorg-x11-server-xephyr, p-cpe:/a:amazon:linux:xorg-x11-server-debuginfo, p-cpe:/a:amazon:linux:xorg-x11-server-common, p-cpe:/a:amazon:linux:xorg-x11-server-devel, p-cpe:/a:amazon:linux:xorg-x11-server-xdmx, p-cpe:/a:amazon:linux:xorg-x11-server-xwayland, p-cpe:/a:amazon:linux:xorg-x11-server-source, cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:xorg-x11-server-xvfb, p-cpe:/a:amazon:linux:xorg-x11-server-xnest, p-cpe:/a:amazon:linux:xorg-x11-server-xorg

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

Exploit Ease: No known exploits are available

Patch Publication Date: 3/8/2025

Vulnerability Publication Date: 2/18/2025

Reference Information

CVE: CVE-2025-26594, CVE-2025-26595, CVE-2025-26596, CVE-2025-26597, CVE-2025-26598, CVE-2025-26599, CVE-2025-26600, CVE-2025-26601

Detections

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