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Critical 2 vendors · 2 advisories

CVE-2026-89712: NFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock

CVE-2026-89712 key facts

CISA KEV
Not listed (catalogue checked )
Highest advisory rating
Critical
CVSS base score
9.8 (NetApp), 7 (Red Hat)
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H · base score 9.8, scored by LinuxAttack vector: network. Attack complexity: low. Privileges required: none. User interaction: none. Scope: unchanged. Confidentiality impact: high. Integrity impact: high. Availability impact: high.
EPSS
0.71% chance of exploitation in the next 30 days (54th percentile). FIRST EPSS, .
Vendor advisories
2 from NetApp, Red Hat
Assigned by
Linux (CNA)
CVE record published
Listed by VulniPulse
Record changed

Ratings, versions and fixes are quoted from the vendor advisories that cover only CVE-2026-89712; each belongs to its advisory, not to every product listed. How records are collected and checked.

Description

In the Linux kernel, the following vulnerability has been resolved: NFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock nfsd4_ssc_expire_umount() walks nn->nfsd_ssc_mount_list with list_for_each_entry_safe(ni, tmp, ...). For each expired entry it sets nsui_busy = true, drops nfsd_ssc_lock to run mntput() on the source vfsmount, then reacquires the lock to list_del + kfree the entry and continue iterating via the macro's saved tmp pointer. The nsui_busy flag protects the current ni from concurrent nfsd4_ssc_setup_dul() finders during the lock-drop window, but it does not pin tmp. Another nfsd RPC thread that fails its source- server mount and reaches nfsd4_ssc_cancel_dul() will, during that same window, take nfsd_ssc_lock, list_del + kfree its own ssc_umount item, and release the lock. If that item is the saved tmp of the expire walk, the next iteration dereferences a freed nfsd4_ssc_umount_item. Restart the walk from the head after the mntput() unlock window so no saved next pointer survives the lock-drop. The list is bounded by the number of active inter-server source mounts (typically small) and the expire delayed-work runs periodically rather than per-IO, so the restart is cheap.

Text from the CVE.org record (Linux).

Vendor advisories for CVE-2026-89712

NetApp

1 advisory
  • Advisory severityCritical9.8

    Critical [CVE-2026-89712] Linux Kernel Vulnerability in NetApp Products

    NTAP-20261002-0016Source published Source updated

    Linux kernel versions 5.10.220 through 5.13.19, 5.14-rc1 through 6.12.108, 6.13-rc1 through 6.18.49 and 6.19-rc1 through 7.2.3 are susceptible to a vulnerability which when successfully exploited could lead to disclosure of sensitive information, addition or modification of data or Denial of Service (DoS). NetApp reports that one or more additional products remain under investigation; review the canonical advisory for current status. NetApp states there is no workaround available at this time.

    Affected products in this advisory
    No product details extracted. Check the source bulletin.
    Source-reported affected versions
    • 5.10.220
    • 5.13.19
    • 5.14
    • 6.12.108

    4 more entries in the full advisory.

    Source-reported fixed versions
    No fixed-version detail extracted. This does not mean no fix exists.
    Mitigation guidance
    No mitigation guidance extracted; consult the source.
    Full advisory and evidenceOpen source bulletin

Red Hat

1 advisory
  • Advisory severityHigh7.0

    High [CVE-2026-89712] restart ssc_expire_umount walk after dropping nfsd_ssc_lock

    CVE-2026-89712Source published Source updated

    In the Linux kernel, the following vulnerability has been resolved: NFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock nfsd4_ssc_expire_umount() walks nn->nfsd_ssc_mount_list with list_for_each_entry_safe(ni, tmp,...). For each expired entry it sets nsui_busy = true, drops nfsd_ssc_lock to run mntput() on the source vfsmount, then reacquires the lock to list_del + kfree the entry and continue iterating via the macro's saved tmp pointer. The nsui_busy flag protects the current ni from concurrent nfsd4_ssc_setup_dul() finders during the lock-drop window, but it does not pin tmp. Another nfsd RPC thread that fails its source- server mount and reaches nfsd4_ssc_cancel_dul() will, during that same window, take nfsd_ssc_lock, list_del + kfree its own ssc_umount item, and release…

    Affected products in this advisory
    • Red Hat Enterprise Linux 10
    • Red Hat Enterprise Linux 6
    • Red Hat Enterprise Linux 9
    • Red Hat OpenShift Container Platform 4

    1 more entries in the full advisory.

    Source-reported affected versions
    Affected-version details not available in this record.
    Source-reported fixed versions
    No fixed-version detail extracted. This does not mean no fix exists.
    Mitigation guidance
    No mitigation guidance extracted; consult the source.
    Full advisory and evidenceOpen source bulletin

References

Timeline

  1. CVE record published
  2. First vendor advisory listed by VulniPulse
  3. CVE record last updated

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