# CVE-2026-89709: lockd, nfsd: RCU-protect nlmsvc_ops dispatch

CVE-2026-89709 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-89709, released September 23, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-89709
- Priority: High
- CVSS: 8.1 (Moderate)
- EPSS: 0.0053
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 11, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-89709

## Description

In the Linux kernel, the following vulnerability has been resolved:  lockd, nfsd: RCU-protect nlmsvc_ops dispatch  nlmsvc_ops is published by nfsd_lockd_init() and cleared by nfsd_lockd_shutdown() with plain stores, while lockd dereferences it unguarded from dispatch sites in fs/lockd/svcsubs.c. The pointer targets nfsd's .rodata and the fopen/fclose callbacks live in nfsd's .text, so a stale load after rmmod nfsd results in either a NULL deref or a module-text use-after-free.  Declare nlmsvc_ops as __rcu, publish via rcu_assign_pointer(), clear via RCU_INIT_POINTER() + synchronize_rcu(). Add a struct module *owner field to nlmsvc_binding and pin the module across indirect calls with try_module_get/module_put. When the binding is torn down, fall back to fput() to avoid leaking struct file references.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.115-2 | [DEBIAN-CVE-2026-89709](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89709.md) | Sep 23, 2026 |
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-89709](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89709.md) | Sep 23, 2026 |

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Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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