CVE-2025-40103: smb: client: Fix refcount leak for cifs_sb_tlink

Q: What is the severity of CVE-2025-40103?

CVE-2025-40103 has been classified with a medium severity level due to its potential impact on Linux kernel stability.

Q: How do I fix CVE-2025-40103?

To fix CVE-2025-40103, ensure that your Linux kernel is updated to the latest stable version that includes the associated patches.

Q: What type of vulnerability is CVE-2025-40103?

CVE-2025-40103 is a reference counting vulnerability impacting the CIFS (Common Internet File System) in the Linux kernel.

Q: Which systems are affected by CVE-2025-40103?

CVE-2025-40103 affects all versions of the Linux kernel that utilize the CIFS protocol.

Q: What is affected in the Linux kernel by CVE-2025-40103?

CVE-2025-40103 addresses refcount inconsistency issues related to `cifs_sb_tlink` within the Linux kernel.

Published Oct 30, 2025

Updated

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

smb: client: Fix refcount leak for cifssbtlink

Fix three refcount inconsistency issues related to cifssbtlink.

Comments for cifssbtlink state that cifsputtlink() needs to be called after successful calls to cifssbtlink(). Three calls fail to update refcount accordingly, leading to possible resource leaks.

Affected Software

242 affected componentsFixes available

Linux Kernel

Microsoft azl3 kernel 6.6.104.2-4

Microsoft azl3 kernel 6.6.112.1-2

Patch available

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-azure*

ubuntu/linux-lts-xenial*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-hwe*

ubuntu/linux-azure*

ubuntu/linux-gcp*

ubuntu/linux-hwe*

ubuntu/linux-hwe-edge*

ubuntu/linux-kvm*

ubuntu/linux-oracle*

ubuntu/linux-fips*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-5.0*

ubuntu/linux-aws-5.3*

ubuntu/linux-aws-5.4*

ubuntu/linux-azure*

ubuntu/linux-azure-4.15*

ubuntu/linux-azure-5.3*

ubuntu/linux-azure-5.4*

ubuntu/linux-azure-edge*

ubuntu/linux-gcp*

ubuntu/linux-gcp-4.15*

ubuntu/linux-gcp-5.3*

ubuntu/linux-gcp-5.4*

ubuntu/linux-gke-4.15*

ubuntu/linux-gke-5.4*

ubuntu/linux-gkeop-5.4*

ubuntu/linux-hwe*

ubuntu/linux-hwe-5.4*

ubuntu/linux-hwe-edge*

ubuntu/linux-ibm-5.4*

ubuntu/linux-kvm*

ubuntu/linux-oem*

ubuntu/linux-oracle*

ubuntu/linux-oracle-5.0*

ubuntu/linux-oracle-5.3*

ubuntu/linux-oracle-5.4*

ubuntu/linux-raspi-5.4*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-5.11*

ubuntu/linux-aws-5.13*

ubuntu/linux-aws-5.15<5.15.0-1112.119~20.04.1

5.15.0-1112.119~20.04.1

ubuntu/linux-aws-5.8*

ubuntu/linux-azure*

ubuntu/linux-azure-5.11*

ubuntu/linux-azure-5.13*

ubuntu/linux-azure-5.15<5.15.0-1117.126~20.04.1

5.15.0-1117.126~20.04.1

ubuntu/linux-azure-5.8*

ubuntu/linux-azure-fde*

ubuntu/linux-azure-fde-5.15<5.15.0-1117.126~20.04.2

5.15.0-1117.126~20.04.2

ubuntu/linux-bluefield*

ubuntu/linux-gcp*

ubuntu/linux-gcp-5.11*

ubuntu/linux-gcp-5.13*

ubuntu/linux-gcp-5.15<5.15.0-1112.122~20.04.1

5.15.0-1112.122~20.04.1

ubuntu/linux-gcp-5.8*

ubuntu/linux-gke*

ubuntu/linux-gke-5.15*

ubuntu/linux-gkeop*

ubuntu/linux-gkeop-5.15*

ubuntu/linux-hwe-5.11*

ubuntu/linux-hwe-5.13*

ubuntu/linux-hwe-5.15<5.15.0-186.196~20.04.1

5.15.0-186.196~20.04.1

ubuntu/linux-hwe-5.8*

ubuntu/linux-ibm*

ubuntu/linux-ibm-5.15<5.15.0-1106.110~20.04.1

5.15.0-1106.110~20.04.1

ubuntu/linux-intel-5.13*

ubuntu/linux-intel-iotg-5.15<5.15.0-1107.113~20.04.1

5.15.0-1107.113~20.04.1

ubuntu/linux-iot*

ubuntu/linux-kvm*

ubuntu/linux-lowlatency-hwe-5.15<5.15.0-184.194~20.04.1

5.15.0-184.194~20.04.1

ubuntu/linux-nvidia-tegra-5.15<5.15.0-1064.66~20.04.1

5.15.0-1064.66~20.04.1

ubuntu/linux-oem-5.10*

ubuntu/linux-oem-5.13*

ubuntu/linux-oem-5.6*

ubuntu/linux-oracle*

ubuntu/linux-oracle-5.11*

ubuntu/linux-oracle-5.13*

ubuntu/linux-oracle-5.15<5.15.0-1109.115~20.04.1

5.15.0-1109.115~20.04.1

ubuntu/linux-oracle-5.8*

ubuntu/linux-raspi*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.11*

ubuntu/linux-riscv-5.15<5.15.0-1106.110~20.04.1

5.15.0-1106.110~20.04.1

ubuntu/linux-riscv-5.8*

ubuntu/linux-xilinx-zynqmp*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux<5.15.0-186.196

5.15.0-186.196

ubuntu/linux-allwinner-5.19*

ubuntu/linux-aws<5.15.0-1112.119

5.15.0-1112.119

ubuntu/linux-aws-5.19*

ubuntu/linux-aws-6.2*

ubuntu/linux-aws-6.5*

ubuntu/linux-aws-6.8<6.8.0-1050.53~22.04.1

6.8.0-1050.53~22.04.1

ubuntu/linux-azure<5.15.0-1117.126

5.15.0-1117.126

ubuntu/linux-azure-5.19*

ubuntu/linux-azure-6.2*

ubuntu/linux-azure-6.5*

ubuntu/linux-azure-6.8<6.8.0-1051.57~22.04.1

6.8.0-1051.57~22.04.1

ubuntu/linux-azure-fde<5.15.0-1117.126

5.15.0-1117.126

ubuntu/linux-azure-fde-5.19*

ubuntu/linux-azure-fde-6.2*

ubuntu/linux-azure-fde-6.8<6.8.0-1058.65~22.04.1

6.8.0-1058.65~22.04.1

ubuntu/linux-gcp<5.15.0-1112.122

5.15.0-1112.122

ubuntu/linux-gcp-5.19*

ubuntu/linux-gcp-6.2*

ubuntu/linux-gcp-6.5*

ubuntu/linux-gcp-6.8<6.8.0-1052.55~22.04.1

6.8.0-1052.55~22.04.1

ubuntu/linux-gke<5.15.0-1108.114

5.15.0-1108.114

ubuntu/linux-gkeop<5.15.0-1095.103

5.15.0-1095.103

ubuntu/linux-hwe-5.19*

ubuntu/linux-hwe-6.2*

ubuntu/linux-hwe-6.5*

ubuntu/linux-hwe-6.8<6.8.0-106.106~22.04.1

6.8.0-106.106~22.04.1

ubuntu/linux-ibm<5.15.0-1106.110

5.15.0-1106.110

ubuntu/linux-ibm-6.8<6.8.0-1049.49~22.04.1

6.8.0-1049.49~22.04.1

ubuntu/linux-intel-iot-realtime*

ubuntu/linux-intel-iotg<5.15.0-1107.113

5.15.0-1107.113

ubuntu/linux-kvm<5.15.0-1104.109

5.15.0-1104.109

ubuntu/linux-lowlatency<5.15.0-184.194

5.15.0-184.194

ubuntu/linux-lowlatency-hwe-5.19*

ubuntu/linux-lowlatency-hwe-6.2*

ubuntu/linux-lowlatency-hwe-6.5*

ubuntu/linux-lowlatency-hwe-6.8<6.8.0-106.106.1~22.04.1

6.8.0-106.106.1~22.04.1

ubuntu/linux-nvidia<5.15.0-1107.108

5.15.0-1107.108

ubuntu/linux-nvidia-6.2*

ubuntu/linux-nvidia-6.5*

ubuntu/linux-nvidia-6.8<6.8.0-1049.52~22.04.1

6.8.0-1049.52~22.04.1

ubuntu/linux-nvidia-tegra<5.15.0-1064.66

5.15.0-1064.66

ubuntu/linux-nvidia-tegra-igx<5.15.0-1053.53

5.15.0-1053.53

ubuntu/linux-oem-5.17*

ubuntu/linux-oem-6.0*

ubuntu/linux-oem-6.1*

ubuntu/linux-oem-6.5*

ubuntu/linux-oracle<5.15.0-1109.115

5.15.0-1109.115

ubuntu/linux-oracle-6.5*

ubuntu/linux-oracle-6.8<6.8.0-1047.48~22.04.1

6.8.0-1047.48~22.04.1

ubuntu/linux-raspi<5.15.0-1106.109

5.15.0-1106.109

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.19*

ubuntu/linux-riscv-6.5*

ubuntu/linux-riscv-6.8<6.8.0-106.106~22.04.1

6.8.0-106.106~22.04.1

ubuntu/linux-starfive-5.19*

ubuntu/linux-starfive-6.2*

ubuntu/linux-starfive-6.5*

ubuntu/linux-xilinx-zynqmp<5.15.0-1075.79

5.15.0-1075.79

ubuntu/linux-bluefield<5.15.0-1096.98

5.15.0-1096.98

ubuntu/linux-intel-iot-realtime<5.15.0-1104.106

5.15.0-1104.106

ubuntu/linux-realtime<5.15.0-1111.120

5.15.0-1111.120

ubuntu/linux-realtime-6.8<6.8.1-1045.46~22.04.1

6.8.1-1045.46~22.04.1

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips<5.15.0-1112.119+fips1

5.15.0-1112.119+fips1

ubuntu/linux-azure-fips<5.15.0-1117.126+fips1

5.15.0-1117.126+fips1

ubuntu/linux-fips<5.15.0-186.196+fips1

5.15.0-186.196+fips1

ubuntu/linux-gcp-fips<5.15.0-1112.122+fips1

5.15.0-1112.122+fips1

ubuntu/linux<6.8.0-106.106

6.8.0-106.106

ubuntu/linux-aws<6.8.0-1050.53

6.8.0-1050.53

ubuntu/linux-aws-6.14*

ubuntu/linux-aws-6.17<6.17.0-1007.7~24.04.1

6.17.0-1007.7~24.04.1

ubuntu/linux-azure<6.8.0-1051.57

6.8.0-1051.57

ubuntu/linux-azure-6.11*

ubuntu/linux-azure-6.14*

ubuntu/linux-azure-fde<6.8.0-1058.65

6.8.0-1058.65

ubuntu/linux-azure-fde-6.14*

ubuntu/linux-azure-nvidia*

ubuntu/linux-azure-nvidia-6.14*

ubuntu/linux-gcp<6.8.0-1052.55

6.8.0-1052.55

ubuntu/linux-gcp-6.11*

ubuntu/linux-gcp-6.14*

ubuntu/linux-gcp-6.17<6.17.0-1008.8~24.04.1

6.17.0-1008.8~24.04.1

ubuntu/linux-gke<6.8.0-1048.53

6.8.0-1048.53

ubuntu/linux-gkeop<6.8.0-1035.38

6.8.0-1035.38

ubuntu/linux-hwe-6.11*

ubuntu/linux-hwe-6.14*

ubuntu/linux-ibm<6.8.0-1049.49

6.8.0-1049.49

ubuntu/linux-lowlatency<6.8.0-106.106.1

6.8.0-106.106.1

ubuntu/linux-lowlatency-hwe-6.11*

ubuntu/linux-nvidia<6.8.0-1049.52

6.8.0-1049.52

ubuntu/linux-nvidia-6.11*

ubuntu/linux-nvidia-6.17<6.17.0-1008.8

6.17.0-1008.8

ubuntu/linux-nvidia-lowlatency<6.8.0-1049.52.1

6.8.0-1049.52.1

ubuntu/linux-nvidia-tegra<6.8.0-1020.20

6.8.0-1020.20

ubuntu/linux-oem-6.11*

ubuntu/linux-oem-6.14*

ubuntu/linux-oem-6.17<6.17.0-1011.11

6.17.0-1011.11

ubuntu/linux-oem-6.8*

ubuntu/linux-oracle<6.8.0-1047.48

6.8.0-1047.48

ubuntu/linux-oracle-6.14*

ubuntu/linux-oracle-6.17<6.17.0-1007.7~24.04.1

6.17.0-1007.7~24.04.1

ubuntu/linux-raspi<6.8.0-1050.54

6.8.0-1050.54

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-6.14*

ubuntu/linux-xilinx<6.8.0-1028.29

6.8.0-1028.29

ubuntu/linux-bluefield<6.8.0-1017.21

6.8.0-1017.21

ubuntu/linux-raspi-realtime<6.8.0-2040.41

6.8.0-2040.41

ubuntu/linux-realtime<6.8.1-1045.46

6.8.1-1045.46

ubuntu/linux-realtime-6.14*

ubuntu/linux-realtime-6.17<6.17.0-1006.7~24.04.1

6.17.0-1006.7~24.04.1

ubuntu/linux-aws-fips<6.8.0-1050.53+fips1

6.8.0-1050.53+fips1

ubuntu/linux-azure-fips<6.8.0-1052.58+fips1

6.8.0-1052.58+fips1

ubuntu/linux-fips<6.8.0-106.106+fips1

6.8.0-106.106+fips1

ubuntu/linux-gcp-fips<6.8.0-1052.55+fips1

6.8.0-1052.55+fips1

ubuntu/linux<6.17.0-14.14

6.17.0-14.14

ubuntu/linux-aws<6.17.0-1007.7

6.17.0-1007.7

ubuntu/linux-azure<6.17.0-1008.8

6.17.0-1008.8

ubuntu/linux-azure-fde*

ubuntu/linux-gcp<6.17.0-1007.7

6.17.0-1007.7

ubuntu/linux-oracle<6.17.0-1007.7

6.17.0-1007.7

ubuntu/linux-raspi<6.17.0-1008.8

6.17.0-1008.8

ubuntu/linux-realtime<6.17.0-1006.7

6.17.0-1006.7

ubuntu/linux-riscv<6.17.0-14.14.1

6.17.0-14.14.1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

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Fixed in 5.15.0-1112.119~20.04.1
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Fixed in 5.15.0-1117.126~20.04.1
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Fixed in 5.15.0-1117.126~20.04.2
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Fixed in 5.15.0-1112.122~20.04.1
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Fixed in 5.15.0-186.196~20.04.1
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Fixed in 5.15.0-1106.110~20.04.1
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Fixed in 5.15.0-1107.113~20.04.1
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Fixed in 5.15.0-184.194~20.04.1
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Fixed in 5.15.0-1064.66~20.04.1
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Fixed in 5.15.0-1109.115~20.04.1
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Fixed in 5.15.0-1106.110~20.04.1
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Fixed in 5.15.0-186.196
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Fixed in 5.15.0-1112.119
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Fixed in 6.8.0-1050.53~22.04.1
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Fixed in 5.15.0-1117.126
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Fixed in 6.8.0-1051.57~22.04.1
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Fixed in 5.15.0-1117.126
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Fixed in 6.8.0-1058.65~22.04.1
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Fixed in 5.15.0-1112.122
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Fixed in 6.8.0-1052.55~22.04.1
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Fixed in 5.15.0-1108.114
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Fixed in 5.15.0-1095.103
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Fixed in 6.8.0-106.106~22.04.1
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Fixed in 5.15.0-1106.110
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Fixed in 6.8.0-1049.49~22.04.1
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Fixed in 5.15.0-1107.113
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Fixed in 5.15.0-1104.109
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Fixed in 5.15.0-184.194
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Fixed in 6.8.0-106.106.1~22.04.1
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Fixed in 5.15.0-1107.108
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Fixed in 6.8.0-1049.52~22.04.1
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Fixed in 5.15.0-1064.66
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Fixed in 5.15.0-1053.53
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Fixed in 5.15.0-1109.115
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Fixed in 6.8.0-1047.48~22.04.1
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Fixed in 5.15.0-1106.109
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Fixed in 6.8.0-106.106~22.04.1
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Fixed in 5.15.0-1075.79
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Fixed in 5.15.0-1096.98
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Fixed in 5.15.0-1104.106
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Fixed in 5.15.0-1111.120
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Fixed in 6.8.1-1045.46~22.04.1
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Fixed in 5.15.0-1112.119+fips1
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Fixed in 5.15.0-1117.126+fips1
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Fixed in 5.15.0-186.196+fips1
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Fixed in 5.15.0-1112.122+fips1
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Fixed in 6.8.0-106.106
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Fixed in 6.8.0-1050.53
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Fixed in 6.17.0-1007.7~24.04.1
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Fixed in 6.8.0-1051.57
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Fixed in 6.8.0-1058.65
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Fixed in 6.8.0-1052.55
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Fixed in 6.17.0-1008.8~24.04.1
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Fixed in 6.8.0-1048.53
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Fixed in 6.8.0-1035.38
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Fixed in 6.8.0-1049.49
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Fixed in 6.8.0-106.106.1
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Fixed in 6.8.0-1049.52
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Fixed in 6.17.0-1008.8
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Fixed in 6.8.0-1049.52.1
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Fixed in 6.8.0-1020.20
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Fixed in 6.17.0-1011.11
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Fixed in 6.8.0-1047.48
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Fixed in 6.17.0-1007.7~24.04.1
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Fixed in 6.8.0-1050.54
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Fixed in 6.8.0-1028.29
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Fixed in 6.8.0-1017.21
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Fixed in 6.8.0-2040.41
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Fixed in 6.8.1-1045.46
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Fixed in 6.17.0-1006.7~24.04.1
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Fixed in 6.8.0-1050.53+fips1
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Fixed in 6.8.0-1052.58+fips1
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Fixed in 6.8.0-106.106+fips1
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Fixed in 6.8.0-1052.55+fips1
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Fixed in 6.17.0-14.14
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Fixed in 6.17.0-1007.7
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Fixed in 6.17.0-1008.8
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Fixed in 6.17.0-1007.7
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Fixed in 6.17.0-1007.7
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Fixed in 6.17.0-1008.8
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Fixed in 6.17.0-1006.7
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Fixed in 6.17.0-14.14.1

Event History

Oct 30, 2025

CVE Published

via MITRE·09:48 AM

Data Sourced

via MITRE·09:48 AM

Description

Data Sourced

via OSV·10:15 AM

DescriptionSeverityAffected Software

Data Sourced

via NVD·10:15 AM

Description

Oct 31, 2025

Data Sourced

via Microsoft·01:09 AM

DescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

What is the severity of CVE-2025-40103?

CVE-2025-40103 has been classified with a medium severity level due to its potential impact on Linux kernel stability.

How do I fix CVE-2025-40103?

To fix CVE-2025-40103, ensure that your Linux kernel is updated to the latest stable version that includes the associated patches.

What type of vulnerability is CVE-2025-40103?

CVE-2025-40103 is a reference counting vulnerability impacting the CIFS (Common Internet File System) in the Linux kernel.

Which systems are affected by CVE-2025-40103?

CVE-2025-40103 affects all versions of the Linux kernel that utilize the CIFS protocol.

What is affected in the Linux kernel by CVE-2025-40103?

CVE-2025-40103 addresses refcount inconsistency issues related to `cifs_sb_tlink` within the Linux kernel.

CVE-2025-40103: smb: client: Fix refcount leak for cifs_sb_tlink

Affected Software

Remediation

Event History

Frequently Asked Questions

What is the severity of CVE-2025-40103?

How do I fix CVE-2025-40103?

What type of vulnerability is CVE-2025-40103?

Which systems are affected by CVE-2025-40103?

What is affected in the Linux kernel by CVE-2025-40103?

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