AlmaLinux 9.6 [TuxCare] Security Update: shim-x64 Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2025:1751552694)

high Nessus Plugin ID 361768

Synopsis

The AlmaLinux host is missing one or more security updates.

Description

The AlmaLinux 9.6 host has a package installed that is affected by multiple vulnerabilities as referenced in the TuxCare ALMALINUX9.6:CLSA-2025:1751552694 advisory.

- There's a possible overflow in handle_image() when shim tries to load and execute crafted EFI executables;
The handle_image() function takes into account the SizeOfRawData field from each section to be loaded. An attacker can leverage this to perform out-of-bound writes into memory. Arbitrary code execution is not discarded in such scenario. (CVE-2022-28737)

- A flaw was found in Shim when an error happened while creating a new ESL variable. If Shim fails to create the new variable, it tries to print an error message to the user; however, the number of parameters used by the logging function doesn't match the format string used by it, leading to a crash under certain circumstances. (CVE-2023-40546)

- A remote code execution vulnerability was found in Shim. The Shim boot support trusts attacker-controlled values when parsing an HTTP response. This flaw allows an attacker to craft a specific malicious HTTP request, leading to a completely controlled out-of-bounds write primitive and complete system compromise.
This flaw is only exploitable during the early boot phase, an attacker needs to perform a Man-in-the- Middle or compromise the boot server to be able to exploit this vulnerability successfully.
(CVE-2023-40547)

- A buffer overflow was found in Shim in the 32-bit system. The overflow happens due to an addition operation involving a user-controlled value parsed from the PE binary being used by Shim. This value is further used for memory allocation operations, leading to a heap-based buffer overflow. This flaw causes memory corruption and can lead to a crash or data integrity issues during the boot phase. (CVE-2023-40548)

- An out-of-bounds read flaw was found in Shim due to the lack of proper boundary verification during the load of a PE binary. This flaw allows an attacker to load a crafted PE binary, triggering the issue and crashing Shim, resulting in a denial of service. (CVE-2023-40549)

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 shim-x64 package based on the guidance in TuxCare advisory ALMALINUX9.6:CLSA-2025:1751552694.

Plugin Details

Severity: High

ID: 361768

File Name: tuxcare_alma_linux_9.6_CLSA-2025-1751552694.nasl

Version: 1.1

Type: Local

Family: Alma Linux Local Security Checks

Published: 10/1/2026

Updated: 10/1/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 94.49

Vendor

Vendor Severity: Important

CVSS v2

Risk Factor: High

Base Score: 7.2

Temporal Score: 5.3

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

CVSS Score Source: CVE-2022-28737

CVSS v3

Risk Factor: High

Base Score: 8.3

Temporal Score: 7.2

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

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

CVSS Score Source: CVE-2023-40547

Vulnerability Information

Required KB Items: Host/local_checks_enabled, Host/cpu, Host/AlmaLinux/release, Host/AlmaLinux/rpm-list, Host/OS/extended-third-party

Exploit Ease: No known exploits are available

Patch Publication Date: 7/3/2025

Vulnerability Publication Date: 6/16/2022

Reference Information

CVE: CVE-2022-28737, CVE-2023-40546, CVE-2023-40547, CVE-2023-40548, CVE-2023-40549, CVE-2023-40550, CVE-2023-40551

CLSA: 2025:1751552694

Detections

Analytics