# CVE-2025-39904: linux: In the Linux kernel, the following vulnerability has been resolved:  arm64: kexec: initialize kexec_buf struct in loa...

CVE-2025-39904 is fixed in linux on 1 platform by DEBIAN-CVE-2025-39904 (version 6.16.8-1), released October 1, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2025-39904
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0013
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 1, 2025

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 6.16.8-1 | [DEBIAN-CVE-2025-39904](https://patchblox.com/security/data/fix/linux/debian-cve-2025-39904.md) | Oct 1, 2025 |

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