CVE-2026-64600
In the Linux kernel, the following vulnerability has been resolved: xfs: resample the data fork mapping after cycling ILOCK xfs_reflink_fill_{cow_hole,delalloc} are both presented with an inode, a data fork mapping, and a cow fork mapping. Unfortunately, these two helpers cycle the ILOCK to grab a transaction, which means that the mappings are stale as soon as we reacquire the ILOCK. Currently we refresh the cow fork mapping by re-calling xfs_find_trim_cow_extent, but we don't refresh the data fork mapping beforehand, which means that the xfs_bmap_trim_cow in that function queries the refcount btree about the wrong physical blocks and returns an inaccurate value in *shared. If *shared is now false, the directio write proceeds with a stale data fork mapping. Fix this by querying the data fork mapping if the sequence counter changes across the ILOCK cycle.
Affected versions
Linux kernel versions
4.11
and later are affected. Fixed in
6.12.96,
6.18.39,
7.1.4,
7.2-rc4
and their respective stable series.
References
7 totalFrequently asked questions
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What is CVE-2026-64600?
CVE-2026-64600 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 4.11 onward and has been patched in 6.12.96, 6.18.39, 7.1.4 and others. CVE-2026-64600 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-2026-64600?
Yes. CVE-2026-64600 has been patched. Fixed versions include 6.12.96, 6.18.39, 7.1.4 and others. If you are running Linux kernel 4.11 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-64600 actively exploited?
No. CVE-2026-64600 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.