namespace: look at the topmost mount for a mount namespace file

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98987
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-23 13:17:20 UTC
Updated2026-10-23 13:17:20 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: namespace: look at the topmost mount for a mount namespace file attach_recursive_mnt() preallocates a mountpoint for the root of the topmost mount of the source so that a mount that already sits at the destination can be put on top of the source or on top of one of its propagated copies. The copies are made without CL_COPY_MNT_NS_FILE so their chain of overmounts is shorter than the source's. It ends below the first bind mount of a mount namespace file. So while the loop walks up the chain of the source it remembers the mountpoint of that mount in "shorter" and the existing mount is put there for the copies. But the loop ends at the topmost mount without ever looking at it. If the topmost mount is the only mount namespace file in the chain "shorter" stays NULL and mnt_change_mountpoint() attaches the existing mount of the copy below the root of the mount namespace file. That's a dentry of nsfs. No path walk in the copy's mount namespace ever gets there. The mount is gone until its parent goes and the copy that took its place can't be unmounted synchronously because it has a child: S bind mount of a file N bind mount of a mount namespace file on top of S A shared mount, B a slave of A, Q mounted on B/file move_mount(S, A/file) cat B/file -> the content of S instead of Q umount B/file -> EBUSY Look at every mount of the chain including the topmost one.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 96f5d2e051653f2cfe9137c5d3c7794c358ffb03 b9c40553f6ceba50042281eef6f701e5fb719726 git Not specified
CNA Linux Linux affected 96f5d2e051653f2cfe9137c5d3c7794c358ffb03 87ecd4c6da146363384a603bd9e90c90e7275536 git Not specified
CNA Linux Linux affected 96f5d2e051653f2cfe9137c5d3c7794c358ffb03 8714b44adac7b10506e1db3ef1710689751f0f10 git Not specified
CNA Linux Linux affected 6.17 Not specified
CNA Linux Linux unaffected 6.17 semver Not specified
CNA Linux Linux unaffected 6.18.57 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.11 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/8714b44adac7b10506e1db3ef1710689751f0f10 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b9c40553f6ceba50042281eef6f701e5fb719726 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/87ecd4c6da146363384a603bd9e90c90e7275536 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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