# CVE-2026-98976: linux: In the Linux kernel, the following vulnerability has been resolved:  namespace: keep the lock on a mount that a propa...

CVE-2026-98976 is fixed in linux on 1 platform by DEBIAN-CVE-2026-98976 (version 7.2.11-1), released October 24, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-98976
- Priority: High
- CVSS: 7.8 (high)
- EPSS: 0.0014
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 23, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:  namespace: keep the lock on a mount that a propagated copy is moved beneath  attach_recursive_mnt() transfers MNT_LOCKED from the top mount to the mount that is moved beneath it with MOVE_MOUNT_BENEATH. This allows the owner of a user namespace to replace its locked /proc or its root. The mount beneath takes on the job of covering the underlying mountpoint allowing the top mount to be unmounted.  Consider two mount namespaces:  (H) The host H has a shared mount P with a secret in P/d (Z) Z is a user namespace made from M. Its copy of P receives     propagation from the host's P and its copy of M's cover on P/d is     locked Z's owner must not get to see P/d.  Now (H) mounts X on P/d. This propagates into (Z). The copy of X lands beneath (Z)'s locked cover. The locked property is transfered from (Z)'s cover to the copy of X propagated beneath it. The cover is now unlocked.  Now (H) unmounts X again. The copy of X in (Z) gets unmounted and the covering mount is left unlocked on top of P/d. (Z) can now unmount it:      Z: umount2(P/d)             = EINVAL            /* the cover is locked */     H: mount X on P/d, umount X                     /* both propagate into Z /*     Z: umount2(P/d)             = 0                 /* the cover is now unlocked */     Z: read P/d/secret          = "covered-by-root" /* secret revealed */  So only transfer the locked property to the mount beneath for mounts the caller has placed. A propagated copy that lands beneath a locked mount is locked as well so that the mount at the bottom of the stack carries a lock the way every check expects. The mount on top of it remains locked to ensure that it keeps covering even if the propagated mount is unmounted again.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.2.11-1 | [DEBIAN-CVE-2026-98976](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98976.md) | Oct 24, 2026 |

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