NULL Pointer Dereference Affecting kernel6.18-tools-devel package, versions <1:6.18.41-94.142.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.16% (7th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNEL618TOOLSDEVEL-19465059
  • published1 Sept 2026
  • disclosed15 Aug 2026

Introduced: 15 Aug 2026

NewCVE-2026-72034  (opens in a new tab)
CWE-476  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel6.18-tools-devel to version 1:6.18.41-94.142.amzn2023 or higher.
This issue was patched in ALAS2023-2026-2071.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel6.18-tools-devel package and not the kernel6.18-tools-devel package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

fhandle: reject detached mounts in capable_wrt_mount()

The recent fhandle RCU fix moved the mount namespace capability check into capable_wrt_mount(), so a non-NULL mnt_namespace survives the ns_capable() dereference. The helper still assumes the later READ_ONCE(mount->mnt_ns) must be non-NULL because may_decode_fh() checked is_mounted() first.

That assumption is not stable. A detached mount from open_tree(..., OPEN_TREE_CLONE) can be dissolved on fput while open_by_handle_at() is between those checks, and umount_tree() can clear mount->mnt_ns. If the helper observes NULL, it dereferences mnt_ns->user_ns and panics.

Return false when the RCU read observes a detached mount. This keeps the relaxed permission path conservative: a mount no longer attached to a namespace cannot authorize open_by_handle_at() access.

CVSS Base Scores

version 3.1