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VulnerabilityPublished Updated

CVE-2026-72034: Linux kernel · fhandle: reject detached mounts in capable_wrt_mount()

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in 15104234c267ebe04b9f9a73e5c2179cc265ff60 : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in 15104234c267ebe04b9f9a73e5c2179cc265ff60, 6ee183d89261bf1d1cf9f06d80a40dab8f36ee55, 6c732471740bc2ac9b0946134f9f551dc75f4369 +1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade Linux kernel to 15104234c267ebe04b9f9a73e5c2179cc265ff60, 6ee183d89261bf1d1cf9f06d80a40dab8f36ee55, 6c732471740bc2ac9b0946134f9f551dc75f4369 or 6c52226072a3c61337b1eec1799bb987748884fa.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 620c266f394932e5decc4b34683a75dfc59dc2f4, < 15104234c267ebe04b9f9a73e5c2179cc265ff60
Fixed in
  • 15104234c267ebe04b9f9a73e5c2179cc265ff60
LinuxLinuxAffected
  • ≥ 620c266f394932e5decc4b34683a75dfc59dc2f4, < 6ee183d89261bf1d1cf9f06d80a40dab8f36ee55
Fixed in
  • 6ee183d89261bf1d1cf9f06d80a40dab8f36ee55
LinuxLinuxAffected
  • ≥ 620c266f394932e5decc4b34683a75dfc59dc2f4, < 6c732471740bc2ac9b0946134f9f551dc75f4369
Fixed in
  • 6c732471740bc2ac9b0946134f9f551dc75f4369
LinuxLinuxAffected
  • ≥ 620c266f394932e5decc4b34683a75dfc59dc2f4, < 6c52226072a3c61337b1eec1799bb987748884fa
Fixed in
  • 6c52226072a3c61337b1eec1799bb987748884fa
LinuxLinuxAffected
  • =6.11
Fixed in–

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.

References

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