Bug 2436826 (CVE-2026-23076)

Summary: CVE-2026-23076 kernel: Linux kernel: Denial of Service in ALSA ctxfi driver due to out-of-bounds access
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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OS: Linux   
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A flaw was found in the Linux kernel's ALSA (Advanced Linux Sound Architecture) ctxfi driver. A local user with access to the sound device and ALSA control interfaces can exploit this out-of-bounds memory access vulnerability by exercising mixer controls. This issue stems from the improper re-initialization of a loop index field, which can cause the system to access memory outside of its allocated bounds. Successful exploitation can lead to a kernel crash or unstable system behavior, resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-02-04 17:05:17 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ALSA: ctxfi: Fix potential OOB access in audio mixer handling

In the audio mixer handling code of ctxfi driver, the conf field is
used as a kind of loop index, and it's referred in the index callbacks
(amixer_index() and sum_index()).

As spotted recently by fuzzers, the current code causes OOB access at
those functions.
| UBSAN: array-index-out-of-bounds in /build/reproducible-path/linux-6.17.8/sound/pci/ctxfi/ctamixer.c:347:48
| index 8 is out of range for type 'unsigned char [8]'

After the analysis, the cause was found to be the lack of the proper
(re-)initialization of conj field.

This patch addresses those OOB accesses by adding the proper
initializations of the loop indices.
Comment 1 Jon Moroney 2026-02-04 19:38:19 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026020420-CVE-2026-23076-b054@gregkh/T