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CVE-2026-98990 Affecting kernel-livepatch-6.12.113-138.209 package, versions <1:1.0-0.amzn2023

Severity

 Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.18% (8th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNELLIVEPATCH612113138209-21812200
  • published29 Oct 2026
  • disclosed23 Oct 2026
Report a new vulnerability Found a mistake?

Introduced: 23 Oct 2026

NewCVE-2026-98990  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel-livepatch-6.12.113-138.209 to version 1:1.0-0.amzn2023 or higher.
This issue was patched in ALAS2023-2026-3335.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-livepatch-6.12.113-138.209 package and not the kernel-livepatch-6.12.113-138.209 package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

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.