# CVE-2026-89684

## Summary

- **CVE ID:** CVE-2026-89684
- **Severity:** HIGH
- **CVSS Score:** 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 14, 2026

## 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.

## Affected Products

- Linux — Linux (624322f1adc58acd0b69f77a6ddc764207e97241)
- Linux — Linux (5.6)
- Linux — Linux (0)
- Linux — Linux (6.12.109)
- Linux — Linux (6.18.50)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)
- Linux — Linux (5.10.270)
- Linux — Linux (5.15.221)
- Linux — Linux (6.1.188)
- Linux — Linux (6.6.157)

## References

- [CNA](https://git.kernel.org/stable/c/21d6c5957f5ca97d7352e60f55ea412beb9419f5)
- [CNA](https://git.kernel.org/stable/c/a631a26a8777bb235eabd478bbbaf26a4db750bf)
- [CNA](https://git.kernel.org/stable/c/c7270f62e7a05a2ee68aa2b74262b658a14463bd)
- [CNA](https://git.kernel.org/stable/c/be3a5c1d857b0dcbc11796cea603ef25834f75b2)
- [CNA](https://git.kernel.org/stable/c/63e18fc65587fd3f7b4c6d70e96d32fc41d82ba3)
- [CNA](https://git.kernel.org/stable/c/6ac469a274e3c7d87fc46ba46d83b95009680407)
- [CNA](https://git.kernel.org/stable/c/8eeca993357a0bc35aaefebfd7462ac7b0a21d9a)
- [CNA](https://git.kernel.org/stable/c/bfeac42d9074e539bacd1898dd8c14b7f5776620)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.51%
- **EPSS Percentile:** 42.1

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._