Incorrect Calculation of Buffer Size in Linux kernel - CVE-2026-23380
Published: March 25, 2026
Vulnerability identifier: #VU124451
CSH Severity: Low
CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-23380
CWE-ID: CWE-131
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper reference counting in the tracing_buffers_mmap_close function when handling memory mappings after a process forks. A local user can trigger a WARN_ON condition by manipulating VMA flags via madvise(MADV_DOFORK), leading to an invalid decrement of the user_mapped reference count and causing a denial of service.
The issue arises when an application removes the VM_DONTCOPY flag using madvise(MADV_DOFORK), allowing the child process to inherit the parent's VMAs without incrementing the reference count.
Affected software
Linux kernel
Debian Linux
linux (Debian package)
Debian Linux
linux (Debian package)
How to mitigate CVE-2026-23380
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
linux (Debian package) - update to 6.12.85-1
linux (Debian package) - update to 6.12.85-1