Integer underflow in Linux kernel - CVE-2026-89902
Published: September 17, 2026
Vulnerability identifier: #VU150378
CSH Severity: Low
CVSS v4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-89902
CWE-ID: CWE-191
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to bypass a BPF cgroup socket creation policy.
The vulnerability exists due to preempt count underflow in the LoongArch kprobe_singlestep_handler() function when processing an ordinary userspace breakpoint using code 11. A local user can issue a code 11 breakpoint and open a socket from a SIGTRAP handler to bypass a BPF cgroup socket creation policy.
The socket can be attributed to the root cgroup rather than the task's own cgroup.
Affected software
Linux kernel
How to mitigate CVE-2026-89902
Install security update from vendor's repository.
External References
- https://git.kernel.org/stable/c/72ce4b24676e8b3b75376c4c559dd81c1ac52d5a
- https://git.kernel.org/stable/c/76395109a051b53860faaec96522ef08ae9e8e27
- https://git.kernel.org/stable/c/a1cb727fa27c2d9c7859729cd90db7bc0f46957f
- https://git.kernel.org/stable/c/c4357ebeee63cb8da1446fc936573a34e68b0f71
- https://git.kernel.org/stable/c/ff40e597d5d98c0c45a4d09df8177202fac9520e