Linux Kernel up to 6.16.7 arm64 /include/linux/kexec.h load_other_segments initialization

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.16.7. Affected by this vulnerability is the function load_other_segments in the library /include/linux/kexec.h of the component arm64. Such manipulation leads to initialization. This vulnerability is referenced as CVE-2025-39904. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.16.7 and classified as critical. Affected by this issue is the function load_other_segments in the library /include/linux/kexec.h of the component arm64. The manipulation with an unknown input leads to a initialization vulnerability. Using CWE to declare the problem leads to CWE-665. The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used. The impact remains unknown. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: arm64: kexec: initialize kexec_buf struct in load_other_segments() Patch series "kexec: Fix invalid field access". The kexec_buf structure was previously declared without initialization. commit bf454ec31add ("kexec_file: allow to place kexec_buf randomly") added a field that is always read but not consistently populated by all architectures. This un-initialized field will contain garbage. This is also triggering a UBSAN warning when the uninitialized data was accessed: ------------[ cut here ]------------ UBSAN: invalid-load in ./include/linux/kexec.h:210:10 load of value 252 is not a valid value for type '_Bool' Zero-initializing kexec_buf at declaration ensures all fields are cleanly set, preventing future instances of uninitialized memory being used. An initial fix was already landed for arm64[0], and this patchset fixes the problem on the remaining arm64 code and on riscv, as raised by Mark. Discussions about this problem could be found at[1][2]. This patch (of 3): The kexec_buf structure was previously declared without initialization. commit bf454ec31add ("kexec_file: allow to place kexec_buf randomly") added a field that is always read but not consistently populated by all architectures. This un-initialized field will contain garbage. This is also triggering a UBSAN warning when the uninitialized data was accessed: ------------[ cut here ]------------ UBSAN: invalid-load in ./include/linux/kexec.h:210:10 load of value 252 is not a valid value for type '_Bool' Zero-initializing kexec_buf at declaration ensures all fields are cleanly set, preventing future instances of uninitialized memory being used.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2025-39904 since 04/16/2025. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 01/07/2026).

The vulnerability scanner Nessus provides a plugin with the ID 269664 (Linux Distros Unpatched Vulnerability : CVE-2025-39904), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.16.8 eliminates this vulnerability. Applying the patch 340cc9a3bd30b25edaf6a9708d41b5f2c10a054a/04d3cd43700a2d0fe4bfb1012a8ec7f2e34a3507 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (269664) and CERT Bund (WID-SEC-2025-2170). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Open Source Linux Kernel
• Dell Secure Connect Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.16.0
• 6.16.1
• 6.16.2
• 6.16.3
• 6.16.4
• 6.16.5
• 6.16.6
• 6.16.7

License

• open-source

Website

• Vendor: https://www.kernel.org/

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