NULL pointer dereference in Linux kernel - CVE-2026-99133
Published: October 29, 2026
Vulnerability identifier: #VU158451
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-476
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service by triggering an unintended AF_IUCV socket disconnect.
The vulnerability exists due to a NULL pointer dereference in iucv_send_ctrl() when iucv_sock_recvmsg() sends a HiperSockets-only window update over the classic z/VM transport. A local user can set SO_MSGLIMIT to 1 and invoke recvmsg() on their own socket to trigger the invalid access through iucv->hs_dev and an unintended disconnect.
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