CVE-2026-64600 xfs: resample the data fork mapping after cycling ILOCK

What is CVE-2026-64600?

CVE-2026-64600 is a high-severity vulnerability in Linux kernel, published on 23 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official 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.

Weakness: CWE-362

Which versions are affected by CVE-2026-64600?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-64600?

Apply the vendor's patch.

Is CVE-2026-64600 being exploited?

There is no known exploitation of CVE-2026-64600 in the wild and no public exploit code.

Public exploit code: 10 proofs of concept on GitHub.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-93050, BELL-CVE-2026-64600, CLSA-2026-1784277735, CLSA-2026-1784278790, DEBIAN-CVE-2026-64600, GHSA-6p99-w6f4-qcvq and 14 more.