lockd, nfsd: RCU-protect nlmsvc_ops dispatch
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 7 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.160, 6.12.114, 6.18.57, 7.2.4, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-89709
- 2026-10-03 Alias added: GHSA-g58f-8h46-hjgv
- 2026-10-16 Fix available: Linux/[email protected], Linux/Linux@836ce2b99bcce6d68c58edd04efbc5cd1fd581af · CNA
- 2026-10-16 1 new reference · CNA
- 2026-10-18 CISA SSVC decision points changed
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-21 CVSS score changed · Red Hat
- 2026-10-21 Fix available: Linux/Linux@43943532c105ea8fe26039a1347cfda4ac0fcadc, Linux/[email protected], Linux/[email protected] +1 · CNA
- 2026-10-21 2 new references · CNA
- 2026-10-30 Fix available: Linux/[email protected], Linux/Linux@cc2f0d79b21be69b891cbd1899daf2a1fdf9df87 · CNA
- 2026-10-30 1 new reference · CNA
- 2026-10-30 Affected versions changed · Red Hat
References
Other 6
- https://git.kernel.org/stable/c/cc2f0d79b21be69b891cbd1899daf2a1fdf9df87
- https://git.kernel.org/stable/c/43943532c105ea8fe26039a1347cfda4ac0fcadc
- https://git.kernel.org/stable/c/6e7495972039f212e336e552b58cac9dd54611c3
- https://git.kernel.org/stable/c/836ce2b99bcce6d68c58edd04efbc5cd1fd581af
- https://git.kernel.org/stable/c/3c461a1820088fb5889d73a6522369bde45527a9
- https://git.kernel.org/stable/c/641e5e20852359b8c31149be4598884e30652f60
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Sources
- CVE-2026-89709 · CVE Program
- CVE-2026-89709 · NVD
- FIRST EPSS
- GHSA-g58f-8h46-hjgv · GitHub Advisory Database · CC BY 4.0
- CVE-2026-89709 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences