Out-of-bounds write in Linux kernel - CVE-2026-74640

Vulnerability identifier: #VU144893

CSH Severity: Low

CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-74640

CWE-ID: CWE-787

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to overwrite kernel memory and cause a denial of service.

The vulnerability exists due to an out-of-bounds write in fcp_meter_ctl_get() when reading ALSA FCP controls with an oversized user-defined meter map. A local user can read a crafted control value to overwrite kernel memory and cause a denial of service.

Installing the oversized meter map requires CAP_SYS_RAWIO, but the created control can later be read by an unprivileged process through /dev/snd/controlC0.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-ibm (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - update to 7.0.0-42.42
linux-aws (Ubuntu package) - update to 7.0.0-1016.17
linux-gcp (Ubuntu package) - update to 7.0.0-1016.18
linux-oracle (Ubuntu package) - update to 7.0.0-1015.16
linux-ibm (Ubuntu package) - update to 7.0.0-1017.17
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-42.42~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1017.17

• https://git.kernel.org/stable/c/620f1e52a46f604635efd0fb78138afd6a513b5d
• https://git.kernel.org/stable/c/bb30e35c36ed00f24fa39aded811f64230a913b0
• https://git.kernel.org/stable/c/bb61dc2ae59026f76db26e1909746908bc5b6f31

• Out-of-bounds write in Linux kernel usb
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more