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Vulnerabilities

Security incident · CVE-2026-98990

namespace: check a submount for references right before unmounting it

Published Oct 23, 2026 · catalog updated Oct 24, 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-2026-98990. EPSS is 0.18%. 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
Unknown—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.18%
Remediation
Advisory link
Affected products
Linux Kernel · vendor Linux Linux

In the Linux kernel, the following vulnerability has been resolved: namespace: check a submount for references right before unmounting it shrink_submounts() and mark_mounts_for_expiry() first collect all the mounts they are allowed to unmount and then unmount them. Whether a mount is busy is decided by propagate_mount_busy() on the tree. But unmounting the first mount changes the tree that the second one propagates into. propagate_umount() moves a surviving overmount off a copy it unmounts and mounts it where the copy was mounted. If that's where the propagated copy of the second victim is looked up the overmount becomes a candidate of the second umount_tree(). It's childless and so trim_one() commits it without looking at its reference count. So a synchronous umount pulls out a busy mount that is in use somewhere else and marks it MNT_SYNC_UMOUNT while it has users: umount2(/tmp/plshrink/p1, 0) = 0 errno 0 cwd is (unreachable) The same two umounts requested one after the other fail with EBUSY. This needs a mount with MNT_SHRINKABLE, i.e., automounted submounts of NFS, AFS and CIFS or the tracefs mount below debugfs. Bind mounts inherit the flag. Check each mount right before it is unmounted under the same hold of namespace_sem and mount_lock as the umount itself. Make sure that the algorithm stays linear.

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 Kernel4.11.0 → 6.6.160; 6.7.0 → 6.12.113; 6.13.0 → 6.18.57
  • vendor Linux Linuxversion unspecified

How to fix CVE-2026-98990

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-2026-98990. EPSS is 0.18%. Act only if a listed version of Linux Linux is installed.

Which versions are affected?

Compare what you have installed with Kernel 4.11.0 → 6.6.160; 6.7.0 → 6.12.113; 6.13.0 → 6.18.57. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.18%. 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: namespace: check a submount for references right before unmounting it shrink_submounts() and mark_mounts_for_expiry() first collect all the mounts they are allowed to unmount and then unmount them. Whether a mount is busy is decided by propagate_mount_busy() on the tree. But unmounting the first mount changes the tree that the sec

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

    Fix available

    Kernel fixed in 6.6.160; Kernel fixed in 6.12.113; 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 6.6.160; 6.7.0

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

    Updated

    In the Linux kernel, the following vulnerability has been resolved: namespace: check a submount for references right before unmounting it shrink_submounts() and mark_mounts_for_expiry() first collect all the mounts they are allowed to unmount and then unmount them. Whether a mount is busy is decided by propagate_mount_busy() on the tree. But unmounting the first mount changes the tree that the sec

Sources

  • CVE.orgVulnerability recordCVE-2026-98990

    In the Linux kernel, the following vulnerability has been resolved: namespace: check a submount for references right before unmounting it shrink_submounts() and mark_mounts_for_expiry() first collect all the mounts they are allowed to unmount and then unmount them. Whether a moun

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-98990

    30-day exploitation probability 0.18%

    first.org
  • OpenSSF OSV / OSV ScannerPackage advisoryCVE-2026-98990

    namespace: check a submount for references right before unmounting it

    osv.dev
  • Tenable CVE DatabaseVulnerability recordCVE-2026-98990

    In the Linux kernel, the following vulnerability has been resolved: namespace: check a submount for references right before unmounting it shrink_submounts() and mark_mounts_for_expiry() first collect all the mounts they are allowed to unmount and then unmount them. Whether a mount is busy is decided by propagate_mount_busy() on the tree. But unmounting the first mount changes the tree that the sec

    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 31, 2026
  • CVE.orgOct 25, 2026
  • OpenSSF OSV / OSV ScannerOct 24, 2026
  • Tenable CVE DatabaseOct 23, 2026