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Vulnerabilities

Vulnerability · CVE-2026-98996

fs: don't silently unmount busy mounts

Published Oct 23, 2026 · catalog updated Oct 25, 2026 · Linux Linux

Last checked Nov 6, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-98996. EPSS is 0.17%. Act only if a listed version of Linux Linux is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.17%
Remediation
Advisory link
Affected products
Linux Kernel · vendor Linux Linux

In the Linux kernel, the following vulnerability has been resolved: fs: don't silently unmount busy mounts The propagate_mount_busy() helper exists to decide whether a synchronous can suceed. It does that by looking at the copies of the victims in the mounts its parent propagates to. One of those functions from propagation hell. It skips a copy that has child mounts except for the case of a single child mount covering the copy's root. That algorithm used to be exact. It isn't anymore. Originally only childless copies were unmounted during propagation. And 1064f874abc0 ("mnt: Tuck mounts under others instead of creating shadow/side mounts.") ended up adding covered mounts to both sides in one go. Along came 99b19d16471e ("mnt: In propgate_umount handle visiting mounts in any order") and that started to unmount more than before: [1]: A copy of a mount is unmounted when each of its children is either its overmount or a copy of the victim itself. In the former case the overmount gets reparented. In the latter case the copy of the victim will end up being unmounted. So propagate_umount() ended up being rewritten without adjusting propagate_mount_busy(). And currently propagate_mount_busy() doesn't look at copies of the victim that have two or more children nor a single child that is not the overmount. So any such copy in [1] is not checked for references. The result is that a synchronous unmount succeeds, pulling out a mount that is still in use. A container can run into this with its own mounts. The host shares a tree with the container and the host has a mount in that tree: mount -t tmpfs none /mnt mount --make-shared /mnt mount -t tmpfs none /mnt/a The container's /mnt is a slave copy of the host mount. The container now takes a detached copy of the tree and mounts that copy beneath its propagated copy of /mnt/a and keeps the file descriptor to the tree open: unshare -m --propagation unchanged mount --make-rslave / fd = open_tree(AT_FDCWD, "/mnt", OPEN_TREE_CLONE | AT

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Linux Kernel4.13.0 → 6.18.57; 6.19.0 → 7.2.11
  • vendor Linux Linuxversion unspecified

How to fix CVE-2026-98996

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-98996. EPSS is 0.17%. Act only if a listed version of Linux Linux is installed.

Which versions are affected?

Compare what you have installed with Kernel 4.13.0 → 6.18.57; 6.19.0 → 7.2.11. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.17%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 23, 2026 · Tenable CVE Database

    Detected

    In the Linux kernel, the following vulnerability has been resolved: fs: don't silently unmount busy mounts The propagate_mount_busy() helper exists to decide whether a synchronous can suceed. It does that by looking at the copies of the victims in the mounts its parent propagates to. One of those functions from propagation hell. It skips a copy that has child mounts except for the case of a single

  2. Oct 24, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    Kernel fixed in 6.18.57; Kernel fixed in 7.2.11

  3. Oct 24, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    Kernel fixed in 6.18.57; 6.19.0

  4. Oct 24, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    In the Linux kernel, the following vulnerability has been resolved: fs: don't silently unmount busy mounts The propagate_mount_busy() helper exists to decide whether a synchronous can suceed. It does that by looking at the copies of the victims in the mounts its parent propagates to. One of those functions from propagation hell. It skips a copy that has child mounts except for the case of a single

  5. Oct 25, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    In the Linux kernel, the following vulnerability has been resolved: fs: don't silently unmount busy mounts The propagate_mount_busy() helper exists to decide whether a synchronous can suceed. It does that by looking at the copies of the victims in the mounts its parent propagates to. One of those functions from propagation hell. It skips a copy that has child mounts except for the case of a single

Sources

  • CVE.orgVulnerability recordCVE-2026-98996

    In the Linux kernel, the following vulnerability has been resolved: fs: don't silently unmount busy mounts The propagate_mount_busy() helper exists to decide whether a synchronous can suceed. It does that by looking at the copies of the victims in the mounts its parent propagates

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-98996

    30-day exploitation probability 0.17%

    first.org
  • OpenSSF OSV / OSV ScannerPackage advisoryCVE-2026-98996

    fs: don't silently unmount busy mounts

    osv.dev
  • Tenable CVE DatabaseVulnerability recordCVE-2026-98996

    In the Linux kernel, the following vulnerability has been resolved: fs: don't silently unmount busy mounts The propagate_mount_busy() helper exists to decide whether a synchronous can suceed. It does that by looking at the copies of the victims in the mounts its parent propagates to. One of those functions from propagation hell. It skips a copy that has child mounts except for the case of a single

    tenable.com

References

Freshness

Last verified in this catalog Nov 6, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSOct 28, 2026
  • CVE.orgOct 25, 2026
  • OpenSSF OSV / OSV ScannerOct 25, 2026
  • Tenable CVE DatabaseOct 23, 2026