Integer underflow in Linux kernel - CVE-2026-89902

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Main Vulnerability Database Vulnerabilities #VU150378

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
Debian Linux
Ubuntu
linux-nvidia-tegra (Ubuntu package)
linux (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-ibm (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux (Debian package)

How to mitigate CVE-2026-89902

Install security update from vendor's repository.

linux-nvidia-tegra (Ubuntu package) - update to 6.8.0-1038.42
linux (Ubuntu package) - update to 7.0.0-42.42
linux-aws (Ubuntu package) - update to 7.0.0-1016.17
linux-gcp (Ubuntu package) - update to 7.0.0-1016.18
linux-oracle (Ubuntu package) - update to 7.0.0-1015.16
linux-ibm (Ubuntu package) - update to 7.0.0-1017.17
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-42.42~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1017.17
linux (Debian package) - update to 6.12.111-1

External References

Related Security Bulletins