CVE-2026-98978namespace: never expire a locked mount
- 8.4HighCVSS base score
- 0.17%Exploitation in 30 daysEPSS · top 93% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: namespace: never expire a locked mount Locked mounts are special. They protect the underlying files and directories from being revealed. do_umount() refuses to unmount locked mounts but shrink_submounts() doesn't. A shrinkable mount can become locked once the owner of a user namespace puts it beneath a locked mount with MOVE_MOUNT_BENEATH. The locked property now moves to the mount at the bottom making it possible to unmount the top mount. So umount() of an unlocked ancestor now expires the bottom mount first and the covered directory is revealed: move_mount(c -> x/hidden, MOVE_MOUNT_BENEATH) = 0 the cover after the lock moved: umount2(x/hidden) = 0 the holder of the lock: umount2(x/hidden) = EINVAL the root of the copy, busy: umount2(x) = EBUSY reads x/hidden/secret: "covered-by-root" So leave a locked mount alone as it dies together with its parent. A plain umount() of an unlocked mount with a locked one below it is EBUSY from now on. It's the same for any other locked child. A lazy umount still takes the whole tree. mark_mounts_for_expiry() never sees a locked mount. lock_mnt_tree() leaves a mount on an expiry list alone and nothing else puts a locked one on such a list. Add an assert for this.
Timeline
ID reserved
By Linux
- 28 days later
· 28 days later
Published
- 18 days later
· 18 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High8.4 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N |
| NVDNVD · Received | 3.1 | High8.4 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.17% · top 93% of all CVEs (15 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.4.
Affected products
- affected 5ff9d8a65ce80efb509ce4e8051394e9ed2cd942 – < 6c8013ea84fcc51cf26aa870b61b5388c7196ed5
- affected 5ff9d8a65ce80efb509ce4e8051394e9ed2cd942 – < 6b8dc3713a76346d212abab46cbfc8d7070f534c
- affected 5ff9d8a65ce80efb509ce4e8051394e9ed2cd942 – < d23265a12e4991ce7aedce670c0b6b598cadb644
- affected 5ff9d8a65ce80efb509ce4e8051394e9ed2cd942 – < f78ddcc872248c7aa1d7e904928441a0be4c6d5d
- affected 3.12
- unaffected < 3.12
- unaffected 6.12.117 – ≤ 6.12.*
- unaffected 6.18.57 – ≤ 6.18.*
- unaffected 7.2.11 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References4
- https://git.kernel.org/stable/c/6c8013ea84fcc51cf26aa870b61b5388c7196ed5 (opens in a new tab)
- https://git.kernel.org/stable/c/6b8dc3713a76346d212abab46cbfc8d7070f534c (opens in a new tab)
- https://git.kernel.org/stable/c/d23265a12e4991ce7aedce670c0b6b598cadb644 (opens in a new tab)
- https://git.kernel.org/stable/c/f78ddcc872248c7aa1d7e904928441a0be4c6d5d (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-108772 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-98978)Record last updated .