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High · 7.5 CVE-2025-40285 EUVD-2025-201570GHSA-7645-fj87-x9w4

smb/server: fix possible refcount leak in smb2_sess_setup()

Published Dec 6, 2025 · 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-5.15 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-aws-6.8 Package: linux-aws-fips Package: linux-azure Package: linux-azure-5.11 Package: linux-azure-5.13 Package: linux-azure-5.15 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-6.2 Package: linux-azure-6.5 Package: linux-azure-6.8 Package: linux-azure-edge Package: linux-azure-fde Package: linux-azure-fde-5.15 Package: linux-azure-fde-5.19 Package: linux-azure-fde-6.14 Package: linux-azure-fde-6.2 Package: linux-azure-fde-6.8 Package: linux-azure-fips Package: linux-azure-nvidia Package: linux-azure-nvidia-6.14 Package: linux-bluefield Package: linux-fips Package: linux-gcp Package: linux-gcp-5.11 Package: linux-gcp-5.13 Package: linux-gcp-5.15 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-gcp-6.8 Package: linux-gcp-fips 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-5.15 Package: linux-hwe-5.19 Package: linux-hwe-5.8 Package: linux-hwe-6.11 Package: linux-hwe-6.14 Package: linux-hwe-6.2 Package: linux-hwe-6.5 Package: linux-hwe-6.8 Package: linux-hwe-edge Package: linux-ibm Package: linux-ibm-5.15 Package: linux-ibm-6.8 Package: linux-intel-5.13 Package: linux-intel-iot-realtime Package: linux-intel-iotg Package: linux-intel-iotg-5.15 Package: linux-kvm Package: linux-lowlatency Package: linux-lowlatency-hwe-5.15 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-lowlatency-hwe-6.8 Package: linux-nvidia Package: linux-nvidia-6.11 Package: linux-nvidia-6.17 Package: linux-nvidia-6.2 Package: linux-nvidia-6.5 Package: linux-nvidia-6.8 Package: linux-nvidia-lowlatency Package: linux-nvidia-tegra Package: linux-nvidia-tegra-5.15 Package: linux-nvidia-tegra-igx 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-5.15 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-oracle-6.8 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-realtime-6.8 Package: linux-riscv Package: linux-riscv-5.11 Package: linux-riscv-5.15 Package: linux-riscv-5.19 Package: linux-riscv-5.8 Package: linux-riscv-6.14 Package: linux-riscv-6.5 Package: linux-riscv-6.8 Package: linux-starfive-5.19 Package: linux-starfive-6.2 Package: linux-starfive-6.5 Package: linux-vmware Package: linux-xilinx Package: linux-xilinx-zynqmp Platform: Linux Ecosystem: Debian Ecosystem: Ubuntu

Description

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

smb/server: fix possible refcount leak in smb2_sess_setup()

Reference count of ksmbd_session will leak when session need reconnect.
Fix this by adding the missing ksmbd_user_session_put().

Affected products

VendorProductAffectedFixed
Linux Linux 6.1.121 – < 6.1.159, 6.6.67 – < 6.6.117, 6.12.6 – < 6.12.59, 5.15.176 – < 5.16, 6.13 6.1.159

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 6.17.9-1 —
Debian 13 linux 6.12.63-1 —
Debian 12 linux 6.1.159-1 —
Debian 11 linux-6.1 6.1.159-1~deb11u1 DLA-4436-1

Ubuntu

Security tracker ↗
ReleasePackageFixed inAdvisory
Ubuntu Nvidia-BlueField 24.04 LTS linux-bluefield 6.8.0-1017.21 —
Ubuntu Nvidia-BlueField 22.04 LTS linux-bluefield No fix yet —
Ubuntu 25.10 linux 6.17.0-14.14 USN-8029-1
Ubuntu 25.10 linux-aws +2 6.17.0-1007.7 USN-8030-1, USN-8029-2
Ubuntu 25.10 linux-azure +1 6.17.0-1008.8 USN-8029-3, USN-8029-1
Ubuntu 25.10 linux-azure-fde No fix yet —
Ubuntu 25.10 linux-realtime 6.17.0-1006.7 USN-8029-1
Ubuntu 25.10 linux-riscv 6.17.0-14.14.1 —
Ubuntu 24.04 LTS linux 6.8.0-106.106 USN-8095-1
Ubuntu 24.04 LTS linux-aws 6.8.0-1050.53 USN-8095-1
Ubuntu 24.04 LTS linux-aws-6.17 +1 6.17.0-1007.7~24.04.1 —
Ubuntu 24.04 LTS linux-azure 6.8.0-1051.57 USN-8125-1
Ubuntu 24.04 LTS linux-azure-fde 6.8.0-1058.65 —
Ubuntu 24.04 LTS linux-azure-nvidia 6.8.0-1039.42 —
Ubuntu 24.04 LTS linux-gcp 6.8.0-1052.55 USN-8095-1
Ubuntu 24.04 LTS linux-gcp-6.17 6.17.0-1008.8~24.04.1 —
Ubuntu 24.04 LTS linux-gke 6.8.0-1048.53 USN-8095-1
Ubuntu 24.04 LTS linux-gkeop 6.8.0-1035.38 USN-8095-1
Ubuntu 24.04 LTS linux-ibm 6.8.0-1049.49 USN-8095-1
Ubuntu 24.04 LTS linux-lowlatency 6.8.0-106.106.1 USN-8095-1
Ubuntu 24.04 LTS linux-nvidia 6.8.0-1049.52 USN-8100-1
Ubuntu 24.04 LTS linux-nvidia-6.17 6.17.0-1008.8 —
Ubuntu 24.04 LTS linux-nvidia-lowlatency 6.8.0-1049.52.1 USN-8100-1
Ubuntu 24.04 LTS linux-nvidia-tegra 6.8.0-1020.20 —
Ubuntu 24.04 LTS linux-oem-6.17 6.17.0-1011.11 USN-8048-1
Ubuntu 24.04 LTS linux-oracle 6.8.0-1047.48 USN-8095-1
Ubuntu 24.04 LTS linux-raspi 6.8.0-1050.54 USN-8095-5
Ubuntu 24.04 LTS linux-riscv +18 No fix yet —
Ubuntu 24.04 LTS linux-xilinx 6.8.0-1028.29 USN-8261-1
Ubuntu 22.04 LTS linux +49 No fix yet —
Ubuntu 22.04 LTS linux-aws-6.8 6.8.0-1050.53~22.04.1 USN-8095-4
Ubuntu 22.04 LTS linux-azure-6.8 6.8.0-1051.57~22.04.1 USN-8126-1
Ubuntu 22.04 LTS linux-azure-fde-6.8 6.8.0-1058.65~22.04.1 —
Ubuntu 22.04 LTS linux-gcp-6.8 6.8.0-1052.55~22.04.1 USN-8095-1
Ubuntu 22.04 LTS linux-hwe-6.8 +1 6.8.0-106.106~22.04.1 USN-8095-1
Ubuntu 22.04 LTS linux-ibm-6.8 6.8.0-1049.49~22.04.1 USN-8095-1
Ubuntu 22.04 LTS linux-lowlatency-hwe-6.8 6.8.0-106.106.1~22.04.1 USN-8095-1
Ubuntu 22.04 LTS linux-nvidia-6.8 6.8.0-1049.52~22.04.1 USN-8100-1
Ubuntu 22.04 LTS linux-oracle-6.8 6.8.0-1047.48~22.04.1 USN-8095-1
Show 8 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 20.04 LTS linux-gke +28 No fix yet —
Ubuntu 18.04 LTS linux-gcp +14 No fix yet —
Ubuntu 16.04 LTS linux-hwe-edge No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-raspi-realtime 6.8.0-2040.41 USN-8095-5
Ubuntu Pro Realtime 24.04 LTS linux-realtime 6.8.1-1045.46 USN-8095-3
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.14 No fix yet —
Ubuntu Pro Realtime 24.04 LTS linux-realtime-6.17 6.17.0-1006.7~24.04.1 —
Ubuntu Pro Realtime 22.04 LTS linux-realtime +1 No fix yet —
Ubuntu Pro Realtime 22.04 LTS linux-realtime-6.8 6.8.1-1045.46~22.04.1 USN-8095-3
Ubuntu Pro FIPS-updates 24.04 LTS linux-aws-fips 6.8.0-1050.53+fips1 USN-8095-2
Ubuntu Pro FIPS-updates 24.04 LTS linux-azure-fips 6.8.0-1052.58+fips1 USN-8165-1
Ubuntu Pro FIPS-updates 24.04 LTS linux-fips 6.8.0-106.106+fips1 USN-8095-2
Ubuntu Pro FIPS-updates 24.04 LTS linux-gcp-fips 6.8.0-1052.55+fips1 USN-8095-2
Ubuntu Pro FIPS-updates 22.04 LTS linux-fips +3 No fix yet —
Ubuntu Pro 20.04 LTS linux-aws-5.15 +10 No fix yet —

Advisories 17

References