namespace: don't copy an unmounted mount tree
In the Linux kernel, the following vulnerability has been resolved: namespace: don't copy an unmounted mount tree may_copy_tree() accepts a mount whose root is an nsfs or pidfs file before it checks whether that mount is mounted. This exception exists for nsfs and pidfs mounts. They are part of no mount namespace so neither check_mnt() nor is_mounted() would let them through and bind-mounting a nsfsfd or a pidfd wouldn't work. Problem is that exception also admits a bind mount of such a file when it was lazily unmounted and is only kept alive by a file descriptor: mount --bind /proc/self/ns/net /tmp/x exec 3< /tmp/x umount -l /tmp/x mount --rbind /proc/self/fd/3 /tmp/y With MS_REC or AT_RECURSIVE copy_tree() doesn't stop at the unmounted mount. It copies every mount that stayed attached to it as well. So if you have a bunch of overmounts over the nsfsfd or the pidfd the whole unmounted stack is copied. That's a bug. So refuse to walk an unmounted tree. Copying its root alone stays possible. So a bind mount of a namespace that is gone can still be recreated from a file descriptor on the old one. The file descriptor pins that mount and its root and __has_locked_children() only reads the direct children which don't leave the parent's list without namespace_sem. The internal mounts carry MNT_NS_INTERNAL instead of NULL and are still walked. Copying an unmounted tree recursively fails with EINVAL.
CVE-2026-98992
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-98992
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "e149ed2b805fefdccf7ccdfc19eca22fdd4514ac",
"lessThan": "86a2d56b1960720bf1844441c0890621e9db2f25",
"versionType": "git"
},
{
"status": "affected",
"version": "e149ed2b805fefdccf7ccdfc19eca22fdd4514ac",
"lessThan": "7e037b1fd339d865737c8accd29abcf40130a5a0",
"versionType": "git"
},
{
"status": "affected",
"version": "e149ed2b805fefdccf7ccdfc19eca22fdd4514ac",
"lessThan": "b47b40c4f058418f9707454543179df240796aad",
"versionType": "git"
},
{
"status": "affected",
"version": "e149ed2b805fefdccf7ccdfc19eca22fdd4514ac",
"lessThan": "8d3527457e183cedee3003c2897314da49488311",
"versionType": "git"
},
{
"status": "affected",
"version": "e149ed2b805fefdccf7ccdfc19eca22fdd4514ac",
"lessThan": "8bacbf6be959973b28b691713a872c12eae69eec",
"versionType": "git"
}
],
"programFiles": [
"fs/namespace.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3.19"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "3.19",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.113",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.57",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.11",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/namespace.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-98992
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #52839 · Revision 1
- Added to Heist Feed
- Publisher date