Use of Uninitialized Variable in Linux kernel - CVE-2026-74339

Vulnerability identifier: #VU142859

CSH Severity: Low

CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-74339

CWE-ID: CWE-457

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to disclose sensitive information.

The vulnerability exists due to improper initialization in snd_seq_read() when copying queued variable-length event headers to userspace. A local user can write a direct variable event to itself and read back a kernel pointer from the returned header to disclose sensitive information.

The issue affects ALSA sequencer variable-length events that use SNDRV_SEQ_EXT_CHAINED internally.

Linux kernel
Ubuntu
linux-nvidia (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-azure-7.0 (Ubuntu package)
linux-azure (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-nvidia (Ubuntu package) - addressed in versions 5.15.0-1112.113, 5.15.0.1112.112
linux-gcp-7.0 (Ubuntu package) - addressed in versions 7.0.0-38.38~24.04.4, 7.0.0-1013.13~24.04.1, 7.0.0-1014.14~24.04.1
linux (Ubuntu package) - addressed in versions 7.0.0-38.38, 7.0.0-38.38.1, 7.0.0-1008.9, 7.0.0-1013.13~24.04.1, 7.0.0-1014.14, 7.0.0-1015.15
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1015.15
linux-azure-7.0 (Ubuntu package) - addressed in versions 7.0.0-1016.16~24.04.1, 7.0.0-1017.17~24.04.1
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1017.17

• https://git.kernel.org/stable/c/14fe4f75fd5309d6b75f8e840ada88912b374207
• https://git.kernel.org/stable/c/6b52211eba213c461f68922708a99d8190c1fcd5
• https://git.kernel.org/stable/c/705dd6dcbc0ea87351c660c1a6443f85f1001c76
• https://git.kernel.org/stable/c/74ac1ce1f4afdb3b80b6742fa28fb86c8c51d31b
• https://git.kernel.org/stable/c/c2ac9287e89916da684c2a548798351e63eb59ee
• https://git.kernel.org/stable/c/e0c3edd86414534cfd179fefe45b38c29c01ae7a
• https://git.kernel.org/stable/c/f29243c211928114f8b906e0a3fee77c236f14c8

• Use of Uninitialized Variable in Linux kernel core seq
• Ubuntu update for linux-gcp-7.0
• Ubuntu update for linux-nvidia
• Ubuntu update for linux-azure-7.0
• Ubuntu update for linux
• Ubuntu update for linux-azure
• Ubuntu update for linux-oem-7.0