Race condition in Linux kernel - CVE-2026-74284

Vulnerability identifier: #VU142916

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-2026-74284

CWE-ID: CWE-362

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to improper state management in the HFSC scheduler class handling in net/sched/sch_hfsc.c when dequeuing packets from a class whose child qdisc becomes empty. A local user can trigger packet processing that causes a class to be marked passive twice to cause a denial of service.

The issue can incorrectly remove a parent with still-backlogged sibling classes from the virtual time tree, causing queued traffic to stop being dequeued.

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/15720cd8fa3fc625146128f89a8e11b0449a20a7
• https://git.kernel.org/stable/c/3a49bbae676fef1ffe548971e6229ae2adeb9d10
• https://git.kernel.org/stable/c/66dbb13eeb2fc339f8f548a9076be4c1a94857b0
• https://git.kernel.org/stable/c/90b662ea25f5e83bb3b8ccec5b93ced810b92fb8
• https://git.kernel.org/stable/c/9221a594c72a1446137926d4c2aa04e345f798dc
• https://git.kernel.org/stable/c/a425c82ff06cda5165e0de3de8c2a445ec1f863e
• https://git.kernel.org/stable/c/b2a017bfcf565721918ec7355a373911d2f2a227
• https://git.kernel.org/stable/c/fc973ecd1a079b9a87c360478542f3a56dea085b

• Race condition in Linux kernel sched
• 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