CVE-2026-98992: Linux kernel · namespace: don't copy an unmounted mount tree
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 28 Oct 2026, 01:59 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
Exploitation evidence
Disclosed: evidence found.
CVE published 23 Oct 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
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10linuxpkg:deb/ubuntu/linux?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix for this vulnerability is available. The Linux kernel has been updated to refuse recursive copying of unmounted mount trees, returning an error instead. Users and administrators should apply the official kernel updates that address this issue to prevent the unintended copying behavior. Since this is a kernel-level fix, upgrading to patched kernel versions is the recommended mitigation.
Description
CVE-2026-98992 is a vulnerability in the Linux kernel's namespace handling where the function may_copy_tree() improperly copies an unmounted mount tree. This occurs because the function accepts mounts whose roots are nsfs or pidfs files before verifying if they are mounted, allowing recursive copying of unmounted mount stacks. The issue arises when bind mounting a namespace file descriptor that was lazily unmounted but still kept alive by a file descriptor, leading to unintended copying of the entire unmounted mount stack. The fix involves refusing to recursively walk unmounted mount trees, returning an error instead.
References
- ubuntu.com/security/CVE-2026-98992 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-98992 (opens in a new tab)
- git.kernel.org/stable/c/7e037b1fd339d865737c8accd29abcf40130a5a0 (opens in a new tab)
- git.kernel.org/stable/c/86a2d56b1960720bf1844441c0890621e9db2f25 (opens in a new tab)
- git.kernel.org/stable/c/8bacbf6be959973b28b691713a872c12eae69eec (opens in a new tab)
- git.kernel.org/stable/c/8d3527457e183cedee3003c2897314da49488311 (opens in a new tab)
- git.kernel.org/stable/c/b47b40c4f058418f9707454543179df240796aad (opens in a new tab)