CVE-2026-89644
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix extent map leak in NOCOW direct I/O write btrfs_dio_iomap_begin() calls btrfs_get_extent(), which returns an extent map reference that must be dropped on all exit paths. For direct writes into a NOCOW range, btrfs_get_blocks_direct_write() keeps using that extent map and asks btrfs_create_dio_extent() to allocate the ordered extent. If that fails, for example because btrfs_alloc_ordered_extent() fails, the function returns the error without dropping the input extent map. The PREALLOC path avoided this by dropping the input extent map before replacing it with the newly created one. Check the error from btrfs_create_dio_extent() before replacing the map and drop the input extent map on failure.
Affected versions
Linux kernel versions
4.7
and later are affected. Fixed in
6.12.111,
6.18.50,
7.2.4,
7.3-rc1
and their respective stable series.
References
4 totalFrequently asked questions
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What is CVE-2026-89644?
CVE-2026-89644 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 4.7 onward and has been patched in 6.12.111, 6.18.50, 7.2.4 and others. CVE-2026-89644 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-89644?
Yes. CVE-2026-89644 has been patched. Fixed versions include 6.12.111, 6.18.50, 7.2.4 and others. If you are running Linux kernel 4.7 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-89644 actively exploited?
No. CVE-2026-89644 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.