CVE-2026-23177: 
Linux Kernel vulnerability analysis and mitigation

CVE-2026-23177 is a Linux kernel vulnerability in the shared memory (shmem) subsystem that causes an infinite loop during truncation of large swap entries under certain race conditions. The flaw was published on February 14, 2026, and affects the Linux kernel's mm/shmem.c component. It has been assigned a CVSS category estimate of Medium by Feedly, with an EPSS score of 0.017% (Feedly). Affected distributions include Debian, Oracle Linux, and Red Hat Enterprise Linux kernels (Feedly).

The root cause is a logic flaw (CWE-835: Loop with Unreachable Exit Condition / Infinite Loop) in the shmem truncation path when handling large swap entries. When index points to the middle of a large swap entry that does not cross the truncation end boundary, find_get_entries() returns the entry with indices[0] equal to index, but shmem_free_swap() fails because the entry's base index is smaller than index. The code then calls shmem_confirm_swap(), checks the end boundary (which passes), and retries with the same index — finding the same entry again indefinitely. The fix involves retrying with a rounded-down index and aborting if that index falls below the truncation range start (Feedly). Patches are referenced in the Linux stable kernel git repository at commits 7b6a0f121d50, 2030dddf9545, and dfc3ab6bd648.

Successful triggering of this vulnerability causes the kernel to enter an infinite loop in the memory management subsystem, resulting in a denial of service (system hang or unresponsive kernel thread). Availability is the primary impact, as the affected process or kernel thread becomes permanently stuck, potentially requiring a system reboot. There is no known confidentiality or integrity impact, and the vulnerability does not enable privilege escalation or lateral movement (Feedly).

Apply the upstream Linux kernel patches referenced in commits 7b6a0f121d50234aab3e7ab9a62ebe826d40a32a, 2030dddf95451b4e7a389f052091e7c4b7b274c6, and dfc3ab6bd64860f8022d69903be299d09be86e11 in the stable kernel tree (Feedly). Distribution-specific updates are available for Debian (DSA-6141-1), Oracle Linux 9 (ELSA-2026-50160, ELSA-2026-50232), and Red Hat Enterprise Linux. Users should update to the latest patched kernel version provided by their distribution vendor as soon as possible. No configuration-based workaround is known.