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CVE-2026-64357: xfs: fix exchmaps reservation limit check

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-25 · updated 2026-09-04

Description

In the Linux kernel, the following vulnerability has been resolved: xfs: fix exchmaps reservation limit check xfs_exchmaps_estimate_overhead() adds the bmbt and rmapbt overhead to a local resblks variable, but the final UINT_MAX check still tests req->resblks. That is the reservation value from before the overhead was added. The computed value is stored back in req->resblks and later passed to xfs_trans_alloc(), whose block reservation argument is unsigned int. Check the computed reservation so the existing limit applies to the value that will be used.

Affected products

• Linux kernel: from 6.10 before 6.12.96; from 6.13 before 6.18.39; from 6.19 before 7.1.4 — fixed in 6.12.96, 6.18.39, 7.1.4

How to fix

Upgrade to a fixed version: Linux kernel 6.12.96, 6.18.39, 7.1.4. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/0a5213bbff62b51c7d4999ac8c7e11ea57d00d45
• https://git.kernel.org/stable/c/4707344b0d36d1012c8a1716e20167cd3afdd5f1
• https://git.kernel.org/stable/c/a62ef2d13d6e7270dd5e88c6082bf2d0edcd5112
• https://git.kernel.org/stable/c/c597c8580d50127fc1221b5a5b653a94d49e23e3

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