Improper Check for Unusual or Exceptional Conditions in Linux kernel - CVE-2026-63955

Vulnerability identifier: #VU138692

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-2026-63955

CWE-ID: CWE-754

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 handling of interrupt context checks in __get_vm_area_node() when allocating memory through vmalloc() with bottom halves disabled. A local user can trigger a code path that reaches vmalloc() in that context to cause a denial of service.

The issue is triggered by a BUG() condition when bottom halves are disabled, even though execution is not in NMI or hard IRQ context.

Linux kernel
Ubuntu
linux-ibm (Ubuntu package)
linux-azure (Ubuntu package)
linux-aws (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-nvidia (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

• https://git.kernel.org/stable/c/04aa71da5f35aacdc9ae9cb5150947daa624f641
• https://git.kernel.org/stable/c/ad7eff07b625f53c3fb513b30d7a8c5a79fbc7ce

• Improper Check for Unusual or Exceptional Conditions in Linux kernel mm
• Ubuntu update for linux-ibm
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-nvidia