CVE-2026-64600
Linux Kernel race condition
- Published23 Jul 2026
Description
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.
CVSS 3.1 breakdown
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HAffected products
Remediation
- https://git.kernel.org/stable/c/206c09b04dc5469c7ff14d8aceff2d47c88078d9
- https://git.kernel.org/stable/c/2f4acd0fcd862e22eab45690ec2c08c80b6ef2e7
- https://git.kernel.org/stable/c/44f891bc088958399eec27f7604928694aa35581
- https://git.kernel.org/stable/c/50f0012da1040f69a4e788cd9aed587c9a04983f
- https://git.kernel.org/stable/c/b8c9aa832b52680ee40d6cab0efb081f9a69df05
- https://git.kernel.org/stable/c/dc11be133efca5fe3a2fb02b016dee825cc12f18
References
- https://cdn2.qualys.com/advisory/2026/07/22/RefluXFS.txt
- https://git.kernel.org/stable/c/206c09b04dc5469c7ff14d8aceff2d47c88078d9
- https://git.kernel.org/stable/c/2f4acd0fcd862e22eab45690ec2c08c80b6ef2e7
- https://git.kernel.org/stable/c/44f891bc088958399eec27f7604928694aa35581
- https://git.kernel.org/stable/c/50f0012da1040f69a4e788cd9aed587c9a04983f
- https://git.kernel.org/stable/c/b8c9aa832b52680ee40d6cab0efb081f9a69df05
- https://git.kernel.org/stable/c/dc11be133efca5fe3a2fb02b016dee825cc12f18
- https://git.kernel.org/stable/c/e705d81a7193dd19e69b8e2bad4696d78a4ea075
- http://www.openwall.com/lists/oss-security/2026/07/22/14
- http://www.openwall.com/lists/oss-security/2026/07/22/18
and 4 more references
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2026-64600 being actively exploited?
CVE-2026-64600 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.47%.
How severe is CVE-2026-64600?
CVE-2026-64600 has a CVSS 3.1 base score of 7.8, rated high. EPSS estimates a 0.47% probability of exploitation.
Which products are affected by CVE-2026-64600?
Affected products include Linux Kernel.
How do I fix CVE-2026-64600?
Upgrade affected software to a fixed version, for example Linux Kernel 5.15.212 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2026-64600 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.