CVE-2026-89841

HIGH
Published Sep 16, 2026 Modified Sep 16, 2026

Description

In the Linux kernel, the following vulnerability has been resolved: f2fs: only redirty pinned folios in redirty_blocks redirty_blocks() pins folios with read_cache_folio() and then walks the same range again with filemap_lock_folio() to redirty them and drop the references it took. Commit 5951fee46bef ("f2fs: Use a folio in redirty_blocks()") changed the second pass to a do/while loop. If read_cache_folio() fails before anything is pinned, page_idx does not advance but the cleanup loop still runs once. If readahead has already populated the failed folio in page cache, that extra iteration finds it and folio_put_refs(folio, 2) drops one reference too many. Later drop_caches or reclaim can then report "BUG: Bad page state". Only redirty the range that was pinned successfully.

Is your site exposed to CVE-2026-89841?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

7.8
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

Frequently Asked Questions

What is CVE-2026-89841? +
In the Linux kernel, the following vulnerability has been resolved: f2fs: only redirty pinned folios in redirty_blocks redirty_blocks() pins folios with read_cache_folio() and then walks the same range again with filemap_lock_folio() to redirty them and drop the references it took. Commit 5951fee46bef ("f2fs: Use a folio in redirty_blocks()") changed the second pass to a do/while loop. If read_cache_folio() fails before anything is pinned, page_idx does not advance but the cleanup loop still runs once. If readahead has already populated the failed folio in page cache, that extra iteration finds it and folio_put_refs(folio, 2) drops one reference too many. Later drop_caches or reclaim can then report "BUG: Bad page state". Only redirty the range that was pinned successfully. It has a CVSS v3.1 base score of 7.8 (HIGH).
How severe is CVE-2026-89841? +
CVE-2026-89841 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.
How do I check if I'm vulnerable to CVE-2026-89841? +
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.

Don't wait for an exploit

Scan your website for vulnerabilities like CVE-2026-89841 — free, no signup required.