Improper locking in Linux kernel - CVE-2026-99133
Published: October 29, 2026
Vulnerability identifier: #VU158452
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-2026-99133
CWE-ID: CWE-667
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to potentially disrupt kernel operation by triggering a sleeping allocation in an atomic context.
The vulnerability exists due to improper locking in iucv_sock_recvmsg() when a window update calls iucv_send_ctrl() while message_q.lock is held with spin_lock_bh(). A local user can invoke recvmsg() to reach a GFP_KERNEL allocation inside the atomic section, potentially causing scheduling errors or a denial of service.
Affected software
Linux kernel
Debian Linux
linux (Debian package)
Debian Linux
linux (Debian package)
How to mitigate CVE-2026-99133
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
linux (Debian package) - update to 6.12.115-2
linux (Debian package) - update to 6.12.115-2