CVE-2026-23177

CVE-2026-23177 is a security vulnerability that is still awaiting full analysis and scoring. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: mm, shmem: prevent infinite loop on truncate race When truncating a large swap entry, shmem_free_swap() returns 0 when the entry's index doesn't match the given index due to lookup alignment. The failure fallback path checks if the entry crosses the end border and aborts when it happens, so truncate won't erase an unexpected entry or range. But one scenario was ignored. When `index` points to the middle of a large swap entry, and the large swap entry doesn't go across the end border, find_get_entries() will return that large swap entry as the first item in the batch with `indices[0]` equal to `index`. The entry's base index will be smaller than `indices[0]`, so shmem_free_swap() will fail and return 0 due to the "base < index" check. The code will then call shmem_confirm_swap(), get the order, check if it crosses the END boundary (which it doesn't), and retry with the same index. The next iteration will find the same entry again at the same index with same indices, leading to an infinite loop. Fix this by retrying with a round-down index, and abort if the index is smaller than the truncate range.

Frequently asked questions

What is CVE-2026-23177?
In the Linux kernel, the following vulnerability has been resolved: mm, shmem: prevent infinite loop on truncate race When truncating a large swap entry, shmem_free_swap() returns 0 when the entry's index doesn't match the given index due to lookup alignment. The failure fallback path checks if the entry crosses the end border and aborts when it happens, so truncate won't erase an unexpected entry or range. But one scenario was ignored. When `index` points to the middle of a large swap entry, and the large swap entry doesn't go across the end border, find_get_entries() will return that large swap entry as the first item in the batch with `indices[0]` equal to `index`. The entry's base index will be smaller than `indices[0]`, so shmem_free_swap() will fail and return 0 due to the "base < index" check. The code will then call shmem_confirm_swap(), get the order, check if it crosses the END boundary (which it doesn't), and retry with the same index. The next iteration will find the same entry again at the same index with same indices, leading to an infinite loop. Fix this by retrying with a round-down index, and abort if the index is smaller than the truncate range.
Is CVE-2026-23177 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-23177?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-23177 have an EU (EUVD) identifier?
Yes. CVE-2026-23177 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5864.
When was CVE-2026-23177 published?
CVE-2026-23177 was published on 2026-02-14 and last updated on 2026-06-17.

References