Out-of-bounds write in Linux kernel - CVE-2026-45990

Vulnerability identifier: #VU132499

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-2026-45990

CWE-ID: CWE-787

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 an out-of-bounds write in krealloc() and kvrealloc() fallback paths when shrinking an object while forcing a new alignment or NUMA migration. A local user can trigger a reallocation with crafted size and alignment parameters to cause a denial of service.

The issue can also result in zero-byte copying during NUMA migration in the reallocation path.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-realtime (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-aws (Ubuntu package)
linux-raspi (Ubuntu package)
linux-azure (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-ibm (Ubuntu package)
linux-azure-fde (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - update to 7.0.0-27.27
linux-realtime (Ubuntu package) - update to 7.0.0-27.27.1
linux-gcp (Ubuntu package) - update to 7.0.0-1007.7
linux-oracle (Ubuntu package) - update to 7.0.0-1007.7
linux-aws (Ubuntu package) - update to 7.0.0-1008.8
linux-raspi (Ubuntu package) - update to 7.0.0-1014.14
linux-azure (Ubuntu package) - update to 7.0.0-1010.10
linux-nvidia (Ubuntu package) - update to 7.0.0-1013.13
linux-ibm (Ubuntu package) - update to 7.0.0-1009.9
linux-azure-fde (Ubuntu package) - update to 7.0.0-1009.9

• https://git.kernel.org/stable/c/082a6d03a2d685a83a332666b500ad3966349588
• https://git.kernel.org/stable/c/38387ccc0fbe38d14fb4c2ad7ee1d7404e5e59fd
• https://git.kernel.org/stable/c/550fa6b5aabb096554536ac1e3ec96b76cbb35fd

• Out-of-bounds write in Linux kernel mm
• Ubuntu update for linux
• Ubuntu update for linux-raspi
• Ubuntu update for linux-nvidia
• Ubuntu update for linux-azure