namespace: check the mounts before reading their parents in pivot_root()

Description

In the Linux kernel, the following vulnerability has been resolved: namespace: check the mounts before reading their parents in pivot_root() path_pivot_root() reads the parents of new_root and of the caller's root and checks whether they are shared before it checks that either mount is in the caller's mount namespace. Only namespace_sem is held. That's fine for a mount that is in the caller's mount namespace. But new_root can be a file descriptor to a mount that has been unmounted and that only the file descriptor keeps alive. If that mount stayed attached to its parent when it was unmounted nothing pins the parent for it. The final mntput() of the parent unhooks the children under mount_lock alone and frees the parent afterwards: pivot_root() close(fd), last ref on the parent ------------ --------------------------------- ex_parent = new_mnt->mnt_parent mntput_no_expire_slowpath() __umount_mnt(new_mnt) cleanup_mnt() call_rcu() IS_MNT_SHARED(ex_parent) BUG: KASAN: slab-use-after-free in path_pivot_root+0xf1a/0x1840 Read of size 4 at addr ffff8881047382f8 by task pivot_widen/157 path_pivot_root+0xf1a/0x1840 __x64_sys_pivot_root+0x165/0x190 The same goes for the caller's root via chroot(). Both outcomes of the check end in EINVAL so nothing but the read itself goes wrong. It's the same thing commit bb4609405752 ("statmount: read the parent of an unmounted mount under mount_lock") fixed for statmount(). Check that both mounts are in the caller's namespace before their parents are read. Every path returns EINVAL either way.

Timeline

Scores

No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.

EPSS (exploitation in 30 days)

0.18% · top 93% of all CVEs (11 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.

Affected products

• Linux · Linux

  • affected e0c9c0afd2fc958ffa34b697972721d81df8a56f – < 43fd2e2ec66e6db26b6ea3e9e7a4c1018455e1b0
  • affected e0c9c0afd2fc958ffa34b697972721d81df8a56f – < 5b5f8d0895cfa9f781ce107225d578897203444f
  • affected e0c9c0afd2fc958ffa34b697972721d81df8a56f – < 3184a2fda996af8fcd6def36020ec023c6279015
  • affected e0c9c0afd2fc958ffa34b697972721d81df8a56f – < a56d4f8f8f4c5d9ac339d5c03a9d90eecd3697fc
  • affected e0c9c0afd2fc958ffa34b697972721d81df8a56f – < 3c2441e21c3df867e4131e0ff784ecdb3a7a55f8
  • affected e0c9c0afd2fc958ffa34b697972721d81df8a56f – < e3aba6900483f64e6c9eb328150dd633b7d36c1c
  • affected e0c9c0afd2fc958ffa34b697972721d81df8a56f – < 3dad2330c89343ba083cf7868779083fd5fbe0fe
  • affected e0c9c0afd2fc958ffa34b697972721d81df8a56f – < 6b7c001eb5857fa09041f47673666060a2e5fc1c
  • affected 84b78514033ff22c443473214ab6d0508394cf7a
  • affected 4.0.2 – < 4.1

• Linux · Linux

  • affected 4.1
  • unaffected < 4.1
  • unaffected 5.10.273 – ≤ 5.10.*
  • unaffected 5.15.224 – ≤ 5.15.*
  • unaffected 6.1.191 – ≤ 6.1.*
  • unaffected 6.6.160 – ≤ 6.6.*
  • unaffected 6.12.114 – ≤ 6.12.*
  • unaffected 6.18.57 – ≤ 6.18.*
  • unaffected 7.2.11 – ≤ 7.2.*
  • unaffected 7.3 – ≤ *

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-2026-108779 (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

[![CVE-2026-98985](https://cveledger.app/badge/CVE-2026-98985.svg)](https://cveledger.app/cve/CVE-2026-98985)

Record last updated 30 Oct 2026, 12:40 UTC.