CVE-2026-89834

Published Sep 16, 2026

Description

In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to migrate all curseg types during free_segment_range In free_segment_range(), the curseg evacuation loop only iterates up to NR_CURSEG_PERSIST_TYPE (0..5), missing non-persistent in-memory curseg types such as CURSEG_COLD_DATA_PINNED and CURSEG_ALL_DATA_ATGC. Even though these in-memory curseg types are not saved in the on-disk checkpoint header, they still occupy active physical segments at runtime. If an active in-memory curseg happens to be allocated within the segment range being truncated during filesystem shrink, failing to evacuate it will cause subsequent writes to the curseg attempting out-of-bounds I/O on the truncated storage range. Fix this by expanding the curseg evacuation loop upper bound to NR_CURSEG_TYPE to ensure all active curseg types are safely migrated out of the target range.

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References

Frequently Asked Questions

What is CVE-2026-89834? +
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to migrate all curseg types during free_segment_range In free_segment_range(), the curseg evacuation loop only iterates up to NR_CURSEG_PERSIST_TYPE (0..5), missing non-persistent in-memory curseg types such as CURSEG_COLD_DATA_PINNED and CURSEG_ALL_DATA_ATGC. Even though these in-memory curseg types are not saved in the on-disk checkpoint header, they still occupy active physical segments at runtime. If an active in-memory curseg happens to be allocated within the segment range being truncated during filesystem shrink, failing to evacuate it will cause subsequent writes to the curseg attempting out-of-bounds I/O on the truncated storage range. Fix this by expanding the curseg evacuation loop upper bound to NR_CURSEG_TYPE to ensure all active curseg types are safely migrated out of the target range.
How do I check if I'm vulnerable to CVE-2026-89834? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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