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Critical · 9.8 CVE-2026-43376 EUVD-2026-28682GHSA-3v8x-c22j-hv4q

ksmbd: fix use-after-free by using call_rcu() for oplock_info

Published May 8, 2026 · Updated Aug 5, 2026 · Assigned by Linux

Vendor: Linux Product: Linux Package: linux Package: linux Package: linux-allwinner-5.19 Package: linux-aws Package: linux-aws-5.0 Package: linux-aws-5.11 Package: linux-aws-5.13 Package: linux-aws-5.19 Package: linux-aws-5.3 Package: linux-aws-5.8 Package: linux-aws-6.14 Package: linux-aws-6.17 Package: linux-aws-6.2 Package: linux-aws-6.5 Package: linux-azure Package: linux-azure-5.11 Package: linux-azure-5.13 Package: linux-azure-5.19 Package: linux-azure-5.3 Package: linux-azure-5.8 Package: linux-azure-6.11 Package: linux-azure-6.14 Package: linux-azure-6.17 Package: linux-azure-6.2 Package: linux-azure-6.5 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.14 Package: linux-azure-fde-6.2 Package: linux-azure-nvidia-6.14 Package: linux-gcp Package: linux-gcp-5.11 Package: linux-gcp-5.13 Package: linux-gcp-5.19 Package: linux-gcp-5.3 Package: linux-gcp-5.8 Package: linux-gcp-6.11 Package: linux-gcp-6.14 Package: linux-gcp-6.17 Package: linux-gcp-6.2 Package: linux-gcp-6.5 Package: linux-gke Package: linux-gke-4.15 Package: linux-gke-5.15 Package: linux-gke-5.4 Package: linux-gkeop Package: linux-gkeop-5.15 Package: linux-gkeop-5.4 Package: linux-hwe Package: linux-hwe-5.11 Package: linux-hwe-5.13 Package: linux-hwe-5.19 Package: linux-hwe-5.8 Package: linux-hwe-6.11 Package: linux-hwe-6.14 Package: linux-hwe-6.17 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-edge Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-lowlatency-hwe-5.19 Package: linux-lowlatency-hwe-6.11 Package: linux-lowlatency-hwe-6.2 Package: linux-lowlatency-hwe-6.5 Package: linux-nvidia-6.11 Package: linux-nvidia-6.17 Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-oem Package: linux-oem-5.10 Package: linux-oem-5.13 Package: linux-oem-5.14 Package: linux-oem-5.17 Package: linux-oem-5.6 Package: linux-oem-6.0 Package: linux-oem-6.1 Package: linux-oem-6.11 Package: linux-oem-6.14 Package: linux-oem-6.17 Package: linux-oem-6.5 Package: linux-oem-6.8 Package: linux-oracle Package: linux-oracle-5.0 Package: linux-oracle-5.11 Package: linux-oracle-5.13 Package: linux-oracle-5.3 Package: linux-oracle-5.8 Package: linux-oracle-6.14 Package: linux-oracle-6.17 Package: linux-oracle-6.5 Package: linux-raspi Package: linux-raspi-realtime Package: linux-raspi2 Package: linux-realtime Package: linux-realtime-6.14 Package: linux-realtime-6.17 Package: linux-riscv Package: linux-riscv-5.11 Package: linux-riscv-5.19 Package: linux-riscv-5.8 Package: linux-riscv-6.14 Package: linux-riscv-6.17 Package: linux-riscv-6.5 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-starfive-6.5 Package: linux-vmware Platform: Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix use-after-free by using call_rcu() for oplock_info

ksmbd currently frees oplock_info immediately using kfree(), even
though it is accessed under RCU read-side critical sections in places
like opinfo_get() and proc_show_files().

Since there is no RCU grace period delay between nullifying the pointer
and freeing the memory, a reader can still access oplock_info
structure after it has been freed. This can leads to a use-after-free
especially in opinfo_get() where atomic_inc_not_zero() is called on
already freed memory.

Fix this by switching to deferred freeing using call_rcu().

Affected products

VendorProductAffectedFixed
Linux Linux 6.6.88 – < 6.6.130, 6.12.25 – < 6.12.78, 6.14.4 – < 6.15, 6.15 6.6.130

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

Debian

Security tracker ↗
ReleasePackageFixed inAdvisory
Debian 14 linux 6.19.10-1 —
Debian 13 linux 6.12.85-1 —

Ubuntu

Security tracker ↗
ReleasePackageFixed inAdvisory
Ubuntu 25.10 linux 6.17.0-40.40 USN-8490-1
Ubuntu 25.10 linux-aws 6.17.0-1019.19 USN-8490-1
Ubuntu 25.10 linux-azure +1 No fix yet —
Ubuntu 25.10 linux-gcp 6.17.0-1020.22 USN-8490-1
Ubuntu 25.10 linux-oracle 6.17.0-1018.18 USN-8490-1
Ubuntu 25.10 linux-raspi 6.17.0-1021.21 USN-8546-1
Ubuntu 25.10 linux-realtime 6.17.0-1017.19 USN-8490-2
Ubuntu 25.10 linux-riscv 6.17.0-40.40.1 —
Ubuntu 24.04 LTS linux-aws-6.17 6.17.0-1019.19~24.04.1 USN-8490-1
Ubuntu 24.04 LTS linux-azure-6.17 6.17.0-1021.21~24.04.1 USN-8604-1
Ubuntu 24.04 LTS linux-gcp-6.17 6.17.0-1020.22~24.04.1 USN-8490-1
Ubuntu 24.04 LTS linux-hwe-6.17 6.17.0-40.40~24.04.1 USN-8545-1
Ubuntu 24.04 LTS linux-nvidia-6.17 6.17.0-1026.26 USN-8508-1
Ubuntu 24.04 LTS linux-oem-6.17 6.17.0-1028.28 USN-8491-1
Ubuntu 24.04 LTS linux-oracle-6.17 +1 6.17.0-1018.18~24.04.1 USN-8605-1, USN-8490-1
Ubuntu 24.04 LTS linux-riscv +19 No fix yet —
Ubuntu 22.04 LTS linux-riscv +32 No fix yet —
Ubuntu 20.04 LTS linux-gke +28 No fix yet —
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Show 2 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.14 No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.17 6.17.0-1017.19~24.04.1 USN-8490-2

Advisories 9

References