CVE-2026-72034: Linux kernel · fhandle: reject detached mounts in capable_wrt_mount()
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 15 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| 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
- git.kernel.org/stable/c/15104234c267ebe04b9f9a73e5c2179cc265ff60 (opens in a new tab)
- git.kernel.org/stable/c/6c52226072a3c61337b1eec1799bb987748884fa (opens in a new tab)
- git.kernel.org/stable/c/6ee183d89261bf1d1cf9f06d80a40dab8f36ee55 (opens in a new tab)
- git.kernel.org/stable/c/6c732471740bc2ac9b0946134f9f551dc75f4369 (opens in a new tab)