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CVE-2026-72034

HIGHCVSS 7.8/10EPSS 0.20%

Last modified

CVE-2026-72034 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. 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. EPSS estimates a 0.20% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
7.8/10

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

EPSS Probability
0.20%

10.2th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 620c266f394932e5decc4b34683a75dfc59dc2f4, < 15104234c267ebe04b9f9a73e5c2179cc265ff60; >= 620c266f394932e5decc4b34683a75dfc59dc2f4, < 6c52226072a3c61337b1eec1799bb987748884fa; >= 620c266f394932e5decc4b34683a75dfc59dc2f4, < 6ee183d89261bf1d1cf9f06d80a40dab8f36ee55; >= 620c266f394932e5decc4b34683a75dfc59dc2f4, < 6c732471740bc2ac9b0946134f9f551dc75f4369
LinuxLinux6.11

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-72034?
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.
How severe is CVE-2026-72034?
CVE-2026-72034 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.20% probability of exploitation in the next 30 days.
How do I fix CVE-2026-72034?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST