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9.8

CVE-2026-89662: Linux kernel NFS server may crash when client disconnects

CVE-2026-89662 · published 1 month ago
Summary

The NFS server part of the Linux kernel can lose track of a client that is being removed, which may cause the server to crash and interrupt file sharing. This happens when a client’s lock information is mishandled during cleanup. Update your Linux kernel to the latest package from your distribution to apply the fix and keep the NFS service running smoothly.

What to do
  • Update debian linux to version 7.2.6-1.
  • Update linux kernel to version 7.2.4.
  • Update bellsoft linux-lts to version 6.18.53-r0.
  • Update debian linux to version 6.12.111-1.
  • Update bellsoft linux-lts to version 6.12.111-r0.
  • Update debian linux-6.12 to version 6.12.111-1~deb12u1.
  • Update bellsoft linux-lts to version 6.1.189-r0.
  • Update linux linux to version a6ead6fff3a7d03e49845f048f7000a2e0d34431 or later.
Affected software
Ecosystem VendorProductAffected versions
Debian:12 debian linux All versions
Debian:14 debian linux < 7.2.6-1
Fix: upgrade to 7.2.6-1
– linux linux < a6ead6fff3a7d03e49845f048f7000a2e0d34431
4.16
Linux linux kernel >= 6.19.0, < 7.2.4
Fix: upgrade to 7.2.4
Ubuntu:Pro:14.04:LTS canonical linux All versions
Ubuntu:Pro:14.04:LTS canonical linux-aws All versions
Ubuntu:Pro:14.04:LTS canonical linux-azure All versions
Ubuntu:Pro:14.04:LTS canonical linux-lts-xenial All versions
Ubuntu:Pro:16.04:LTS canonical linux-aws-hwe All versions
Ubuntu:Pro:16.04:LTS canonical linux-gcp All versions
Ubuntu:Pro:16.04:LTS canonical linux-hwe All versions
Ubuntu:16.04:LTS canonical linux-hwe-edge All versions
Ubuntu:Pro:16.04:LTS canonical linux-kvm All versions
Ubuntu:Pro:16.04:LTS canonical linux-oracle All versions
Ubuntu:Pro:FIPS:16.04:LTS canonical linux-fips All versions
Ubuntu:18.04:LTS canonical linux-aws-5.0 All versions
Ubuntu:18.04:LTS canonical linux-aws-5.3 All versions
Ubuntu:Pro:18.04:LTS canonical linux-aws-5.4 All versions
Ubuntu:Pro:18.04:LTS canonical linux-azure-4.15 All versions
Ubuntu:18.04:LTS canonical linux-azure-5.3 All versions
Ubuntu:Pro:18.04:LTS canonical linux-azure-5.4 All versions
Ubuntu:18.04:LTS canonical linux-azure-edge All versions
Ubuntu:Pro:18.04:LTS canonical linux-gcp-4.15 All versions
Ubuntu:18.04:LTS canonical linux-gcp-5.3 All versions
Ubuntu:Pro:18.04:LTS canonical linux-gcp-5.4 All versions
Ubuntu:18.04:LTS canonical linux-gke-4.15 All versions
Ubuntu:18.04:LTS canonical linux-gke-5.4 All versions
Ubuntu:18.04:LTS canonical linux-gkeop-5.4 All versions
Ubuntu:Pro:18.04:LTS canonical linux-hwe-5.4 All versions
Ubuntu:Pro:18.04:LTS canonical linux-ibm-5.4 All versions
Ubuntu:18.04:LTS canonical linux-oem All versions
Ubuntu:18.04:LTS canonical linux-oracle-5.0 All versions
Ubuntu:18.04:LTS canonical linux-oracle-5.3 All versions
Ubuntu:Pro:18.04:LTS canonical linux-oracle-5.4 All versions
Ubuntu:Pro:18.04:LTS canonical linux-raspi-5.4 All versions
Ubuntu:Pro:FIPS-updates:18.04:LTS canonical linux-aws-fips All versions
Ubuntu:Pro:FIPS-updates:18.04:LTS canonical linux-azure-fips All versions
Ubuntu:Pro:FIPS-updates:18.04:LTS canonical linux-gcp-fips All versions
Ubuntu:20.04:LTS canonical linux-aws-5.11 All versions
Ubuntu:20.04:LTS canonical linux-aws-5.13 All versions
Ubuntu:Pro:20.04:LTS canonical linux-aws-5.15 All versions
Ubuntu:20.04:LTS canonical linux-aws-5.8 All versions
Ubuntu:20.04:LTS canonical linux-azure-5.11 All versions
Ubuntu:20.04:LTS canonical linux-azure-5.13 All versions
Ubuntu:Pro:20.04:LTS canonical linux-azure-5.15 All versions
Ubuntu:20.04:LTS canonical linux-azure-5.8 All versions
Ubuntu:20.04:LTS canonical linux-azure-fde All versions
Ubuntu:Pro:20.04:LTS canonical linux-azure-fde-5.15 All versions
Ubuntu:Pro:20.04:LTS canonical linux-bluefield All versions
Ubuntu:20.04:LTS canonical linux-gcp-5.11 All versions
Showing 50 of 178. Show the rest
Ecosystem VendorProductAffected versions
Ubuntu:20.04:LTS canonical linux-gcp-5.13 All versions
Ubuntu:Pro:20.04:LTS canonical linux-gcp-5.15 All versions
Ubuntu:20.04:LTS canonical linux-gcp-5.8 All versions
Ubuntu:20.04:LTS canonical linux-gke All versions
Ubuntu:20.04:LTS canonical linux-gke-5.15 All versions
Ubuntu:20.04:LTS canonical linux-gkeop All versions
Ubuntu:20.04:LTS canonical linux-gkeop-5.15 All versions
Ubuntu:20.04:LTS canonical linux-hwe-5.11 All versions
Ubuntu:20.04:LTS canonical linux-hwe-5.13 All versions
Ubuntu:Pro:20.04:LTS canonical linux-hwe-5.15 All versions
Ubuntu:20.04:LTS canonical linux-hwe-5.8 All versions
Ubuntu:Pro:20.04:LTS canonical linux-ibm All versions
Ubuntu:Pro:20.04:LTS canonical linux-ibm-5.15 All versions
Ubuntu:20.04:LTS canonical linux-intel-5.13 All versions
Ubuntu:Pro:20.04:LTS canonical linux-intel-iotg-5.15 All versions
Ubuntu:Pro:20.04:LTS canonical linux-iot All versions
Ubuntu:Pro:20.04:LTS canonical linux-lowlatency-hwe-5.15 All versions
Ubuntu:Pro:20.04:LTS canonical linux-nvidia-tegra-5.15 All versions
Ubuntu:20.04:LTS canonical linux-oem-5.10 All versions
Ubuntu:20.04:LTS canonical linux-oem-5.13 All versions
Ubuntu:20.04:LTS canonical linux-oem-5.14 All versions
Ubuntu:20.04:LTS canonical linux-oem-5.6 All versions
Ubuntu:20.04:LTS canonical linux-oracle-5.11 All versions
Ubuntu:20.04:LTS canonical linux-oracle-5.13 All versions
Ubuntu:Pro:20.04:LTS canonical linux-oracle-5.15 All versions
Ubuntu:20.04:LTS canonical linux-oracle-5.8 All versions
Ubuntu:Pro:20.04:LTS canonical linux-raspi All versions
Ubuntu:20.04:LTS canonical linux-raspi2 All versions
Ubuntu:20.04:LTS canonical linux-riscv All versions
Ubuntu:20.04:LTS canonical linux-riscv-5.11 All versions
Ubuntu:Pro:20.04:LTS canonical linux-riscv-5.15 All versions
Ubuntu:20.04:LTS canonical linux-riscv-5.8 All versions
Ubuntu:Pro:20.04:LTS canonical linux-xilinx-zynqmp All versions
Ubuntu:22.04:LTS canonical linux-allwinner-5.19 All versions
Ubuntu:22.04:LTS canonical linux-aws-5.19 All versions
Ubuntu:22.04:LTS canonical linux-aws-6.2 All versions
Ubuntu:22.04:LTS canonical linux-aws-6.5 All versions
Ubuntu:22.04:LTS canonical linux-aws-6.8 All versions
Ubuntu:22.04:LTS canonical linux-azure-5.19 All versions
Ubuntu:22.04:LTS canonical linux-azure-6.2 All versions
Ubuntu:22.04:LTS canonical linux-azure-6.5 All versions
Ubuntu:22.04:LTS canonical linux-azure-6.8 All versions
Ubuntu:22.04:LTS canonical linux-azure-fde-5.19 All versions
Ubuntu:22.04:LTS canonical linux-azure-fde-6.2 All versions
Ubuntu:22.04:LTS canonical linux-azure-fde-6.8 All versions
Ubuntu:22.04:LTS canonical linux-gcp-5.19 All versions
Ubuntu:22.04:LTS canonical linux-gcp-6.2 All versions
Ubuntu:22.04:LTS canonical linux-gcp-6.5 All versions
Ubuntu:22.04:LTS canonical linux-gcp-6.8 All versions
Ubuntu:22.04:LTS canonical linux-hwe-5.19 All versions
Ubuntu:22.04:LTS canonical linux-hwe-6.2 All versions
Ubuntu:22.04:LTS canonical linux-hwe-6.5 All versions
Ubuntu:22.04:LTS canonical linux-hwe-6.8 All versions
Ubuntu:22.04:LTS canonical linux-ibm-6.8 All versions
Ubuntu:22.04:LTS canonical linux-intel-iot-realtime All versions
Ubuntu:22.04:LTS canonical linux-intel-iotg All versions
Ubuntu:22.04:LTS canonical linux-lowlatency All versions
Ubuntu:22.04:LTS canonical linux-lowlatency-hwe-5.19 All versions
Ubuntu:22.04:LTS canonical linux-lowlatency-hwe-6.2 All versions
Ubuntu:22.04:LTS canonical linux-lowlatency-hwe-6.5 All versions
Ubuntu:22.04:LTS canonical linux-lowlatency-hwe-6.8 All versions
Ubuntu:22.04:LTS canonical linux-nvidia All versions
Ubuntu:22.04:LTS canonical linux-nvidia-6.2 All versions
Ubuntu:22.04:LTS canonical linux-nvidia-6.5 All versions
Ubuntu:22.04:LTS canonical linux-nvidia-6.8 All versions
Ubuntu:22.04:LTS canonical linux-nvidia-tegra All versions
Ubuntu:22.04:LTS canonical linux-nvidia-tegra-igx All versions
Ubuntu:22.04:LTS canonical linux-oem-5.17 All versions
Ubuntu:22.04:LTS canonical linux-oem-6.0 All versions
Ubuntu:22.04:LTS canonical linux-oem-6.1 All versions
Ubuntu:22.04:LTS canonical linux-oem-6.5 All versions
Ubuntu:22.04:LTS canonical linux-oracle-6.5 All versions
Ubuntu:22.04:LTS canonical linux-oracle-6.8 All versions
Ubuntu:22.04:LTS canonical linux-realtime All versions
Ubuntu:22.04:LTS canonical linux-riscv-5.19 All versions
Ubuntu:22.04:LTS canonical linux-riscv-6.5 All versions
Ubuntu:22.04:LTS canonical linux-riscv-6.8 All versions
Ubuntu:22.04:LTS canonical linux-starfive-5.19 All versions
Ubuntu:22.04:LTS canonical linux-starfive-6.2 All versions
Ubuntu:22.04:LTS canonical linux-starfive-6.5 All versions
Ubuntu:Pro:Realtime:22.04:LTS canonical linux-realtime-6.8 All versions
Ubuntu:24.04:LTS canonical linux-aws-6.14 All versions
Ubuntu:24.04:LTS canonical linux-aws-6.17 All versions
Ubuntu:24.04:LTS canonical linux-aws-7.0 All versions
Ubuntu:24.04:LTS canonical linux-azure-6.11 All versions
Ubuntu:24.04:LTS canonical linux-azure-6.14 All versions
Ubuntu:24.04:LTS canonical linux-azure-6.17 All versions
Ubuntu:24.04:LTS canonical linux-azure-7.0 All versions
Ubuntu:24.04:LTS canonical linux-azure-fde-6.14 All versions
Ubuntu:24.04:LTS canonical linux-azure-fde-6.17 All versions
Ubuntu:24.04:LTS canonical linux-azure-fde-7.0 All versions
Ubuntu:24.04:LTS canonical linux-azure-nvidia All versions
Ubuntu:24.04:LTS canonical linux-azure-nvidia-6.14 All versions
Ubuntu:24.04:LTS canonical linux-gcp-6.11 All versions
Ubuntu:24.04:LTS canonical linux-gcp-6.14 All versions
Ubuntu:24.04:LTS canonical linux-gcp-6.17 All versions
Ubuntu:24.04:LTS canonical linux-gcp-7.0 All versions
Ubuntu:24.04:LTS canonical linux-hwe-6.11 All versions
Ubuntu:24.04:LTS canonical linux-hwe-6.14 All versions
Ubuntu:24.04:LTS canonical linux-hwe-6.17 All versions
Ubuntu:24.04:LTS canonical linux-hwe-7.0 All versions
Ubuntu:24.04:LTS canonical linux-lowlatency-hwe-6.11 All versions
Ubuntu:24.04:LTS canonical linux-nvidia-6.11 All versions
Ubuntu:24.04:LTS canonical linux-nvidia-6.17 All versions
Ubuntu:24.04:LTS canonical linux-nvidia-7.0 All versions
Ubuntu:24.04:LTS canonical linux-nvidia-lowlatency All versions
Ubuntu:24.04:LTS canonical linux-oem-6.11 All versions
Ubuntu:24.04:LTS canonical linux-oem-6.14 All versions
Ubuntu:24.04:LTS canonical linux-oem-6.17 All versions
Ubuntu:24.04:LTS canonical linux-oem-6.8 All versions
Ubuntu:24.04:LTS canonical linux-oracle-6.14 All versions
Ubuntu:24.04:LTS canonical linux-oracle-6.17 All versions
Ubuntu:24.04:LTS canonical linux-oracle-7.0 All versions
Ubuntu:24.04:LTS canonical linux-raspi-realtime All versions
Ubuntu:24.04:LTS canonical linux-riscv-6.14 All versions
Ubuntu:24.04:LTS canonical linux-riscv-6.17 All versions
Ubuntu:24.04:LTS canonical linux-riscv-7.0 All versions
Ubuntu:24.04:LTS canonical linux-xilinx All versions
Ubuntu:Pro:Realtime:24.04:LTS canonical linux-realtime-6.14 All versions
Ubuntu:Pro:Realtime:24.04:LTS canonical linux-realtime-6.17 All versions
Ubuntu:26.04:LTS canonical linux-nvidia-bos All versions
Ubuntu:26.04:LTS canonical linux-oem-7.0 All versions
Alpaquita:23 bellsoft linux-lts >= 6.1.182-r0
>= 6.1.182-r0, < 6.1.189-r0
Fix: upgrade to 6.1.189-r0
Alpaquita:25 bellsoft linux-lts >= 6.12.103-r0
>= 6.12.103-r0, < 6.12.111-r0
Fix: upgrade to 6.12.111-r0
Alpaquita:stream bellsoft linux-lts >= 6.18.46-r0
>= 6.18.46-r0, < 6.18.53-r0
Fix: upgrade to 6.18.53-r0
Debian:13 debian linux < 6.12.111-1
Fix: upgrade to 6.12.111-1
Debian:12 debian linux-6.12 < 6.12.111-1~deb12u1
Fix: upgrade to 6.12.111-1~deb12u1
Ubuntu:24.04:LTS canonical linux-vmware All versions
Original advisory text
BELL-CVE-2026-89662
In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent lock owner use-after-free during client teardown __destroy_client() releases a client's open owners, but a lock owner whose only reference is a blocked lock (nbl) stays on cl_ownerstr_hashtbl. client_has_state() does not count a bare owner, so DESTROY_CLIENTID can reach __destroy_client() with such owners present. __destroy_client() then walks the table, calling remove_blocked_locks() on each owner without a reference. Freeing a blocked lock drops the owner reference held via flc_owner. The per-net laundromat reaps blocked locks from nn->blocked_locks_lru independently of client state. The two paths share blocked_locks_lock only for the list splice, not the owner's lifetime. The laundromat therefore frees the owner as __destroy_client() dereferences it, a NULL dereference in remove_blocked_locks(). nfsd4_release_lockowner() holds a reference across the same call; __destroy_client() does not. Hold cl_lock across the walk, taking a reference and unhashing each owner, then drop it before remove_blocked_locks() and nfs4_put_stateowner(), which take blocked_locks_lock and cl_lock.
Severity
9.8 Critical
Exploitation
<1% chance of attack within 30 days
Timeline
Published11 Sep 2026
Updated12 Oct 2026
First seen11 Sep 2026
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