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VulnerabilityPublished Updated

CVE-2026-89684: Linux kernel · nfsd: fix cpntf publish race in nfs4_init_cp_state

Affects Linux kernelSource GCVE Database

0

Not known to be exploited · CVSS 7.5 High.

Data as of 28 Oct 2026, 01:01 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-5.5 – 7.0.0-38.38
23 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1002.2 – 7.0.0-1014.14
15 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1003.3 – 7.0.0-1017.17
15 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threatsAffected
  • 7.0.0-1003.3 – 7.0.0-1016.16
9 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threatsAffected
  • 6.17.0-1002.2 – 7.0.0-1014.14
13 affected builds
Fixed in–
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threatsAffected
  • 7.0.0-1002.3 – 7.0.0-1008.9
6 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix cpntf publish race in nfs4_init_cp_state nfs4_alloc_init_cpntf_state() published the new cpntf entry into the s2s_cp_stateids IDR (with cs_type set) in one s2s_cp_lock section, then took the lock again to list_add() it onto p_stid->sc_cp_list. In the gap the entry is reachable by so_id but cp_list is still {NULL,NULL} from kzalloc. A racing OFFLOAD_CANCEL (so_id is echoed to the client as cnr_stateid, so any NFSv4.2 client can drive it) reaches manage_cpntf_state() -> _free_cpntf_state_locked() and does list_del() on the zeroed list_head, oopsing the server. Fold the cs_type assignment and the list_add() into the same critical section as idr_alloc_cyclic(), so a concurrent lookup either misses the entry or sees a fully linked cp_list. INIT_LIST_HEAD() the entry after allocation and switch _free_cpntf_state_locked() to list_del_init() so a stale unlink is a no-op. nfs4_init_copy_state() passes NULL p_stid and skips the list_add, preserving NFS4_COPY_STID semantics.

References

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