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Linux KernelOperating system · Linux

CVE-2026-64294

MEDIUM · 5.5 CVSS v3.1 Published 2026-07-25
Fix available
A fix is available. Upgrade to 6.6.145 / 6.12.96 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click 4 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: mm: do file ownership checks with the proper mount idmap Ever since idmapped mounts were introduced, inode ownership checks (for side-channel protection) in mincore() and madvise(MADV_PAGEOUT) were done against the nop_mnt_idmap, which completely ignores the file's mount's idmap. This results in odd edgecases like: 1) mount/bind-mount with an idmap userA:userB:1 2) userB runs an owner_or_capable() check on file that is owned by userA on-disk/in-memory, but owned by userB after idmap translation 3) owner_or_capable() mysteriously fails as the correct idmap wasn't supplied In the case of mincore/madvise MADV_PAGEOUT, this is usually benign, because file_permission(file, MAY_WRITE) will probably succeed, as it uses the proper idmap internally, but it does not need to be the case on e.g a 0444 file where even the owner itself doesn't have permissions to write to it. Since this is clearly not trivial to get right, introduce a file_owner_or_capable() that can carry the correct semantics, and switch the various users in mm to it. The issue was found by manual code inspection & an off-list discussion with Jan Kara.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 5.12, < 6.6.145>= 6.7, < 6.12.96>= 6.13, < 6.18.39>= 6.19, < 7.1.4= 7.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.6.145 / 6.12.96 / 6.18.39 or later
Fixed in 6.6.1456.12.966.18.39
Recommended fix High confidence

6.6.145+ / 6.12.96+ / 6.18.39+ / 7.1.4+ (depending on which branch you're on)

  1. Identify the current running kernel version using `uname -r`
  2. Determine which kernel branch your current version belongs to (e.g., 6.6.y, 6.12.y, 6.18.y, or 7.1.y)
  3. Upgrade the Linux kernel to the fixed version for your branch: for 6.6.x upgrade to >= 6.6.145, for 6.7-6.12.x upgrade to >= 6.12.96, for 6.13-6.18.x upgrade to >= 6.18.39, for 6.19-7.1.x upgrade to >= 7.1.4
  4. Update GRUB bootloader configuration if necessary using `update-grub` or `grub2-mkconfig`
  5. Reboot the system into the new kernel
  6. Verify the new kernel is running with `uname -r` and confirm the version meets or exceeds the minimum fixed version
Caveat Kernel upgrades may require restarting services; ensure compatibility with existing system configurations and drivers

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-64294 in production — separate from our analysis above.

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