CVE-2025-40204: sctp: Fix MAC comparison to be constant-time

Q: What is the severity of CVE-2025-40204?

CVE-2025-40204 has been classified as a moderate severity vulnerability due to its potential for timing attacks.

Q: How do I fix CVE-2025-40204?

To resolve CVE-2025-40204, update your Linux kernel to the latest version where the issue has been addressed with constant-time MAC comparison.

Q: What software is affected by CVE-2025-40204?

CVE-2025-40204 affects the Linux kernel, particularly versions prior to the fix being applied.

Q: What type of attack does CVE-2025-40204 prevent?

CVE-2025-40204 prevents timing attacks by ensuring MAC comparisons are conducted in constant time.

Q: Is CVE-2025-40204 still a risk if I update regularly?

CVE-2025-40204 is mitigated by updating to the patched version of the Linux kernel, reducing the risk significantly.

Published Nov 12, 2025

Updated

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

sctp: Fix MAC comparison to be constant-time

To prevent timing attacks, MACs need to be compared in constant time. Use the appropriate helper function for this.

Affected Software

241 affected componentsFixes available

Linux Linux kernel

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<5.15.0-1100.107~20.04.2

5.15.0-1100.107~20.04.2

ubuntu/linux-aws-5.8*

ubuntu/linux-azure*

ubuntu/linux-azure-5.11*

ubuntu/linux-azure-5.13*

ubuntu/linux-azure-5.15<5.15.0-1110.119~20.04.1

5.15.0-1110.119~20.04.1

ubuntu/linux-azure-5.8*

ubuntu/linux-azure-fde*

ubuntu/linux-bluefield*

ubuntu/linux-gcp*

ubuntu/linux-gcp-5.11*

ubuntu/linux-gcp-5.13*

ubuntu/linux-gcp-5.15<5.15.0-1100.109~20.04.1

5.15.0-1100.109~20.04.1

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<5.15.0-170.180~20.04.3

5.15.0-170.180~20.04.3

ubuntu/linux-hwe-5.8*

ubuntu/linux-ibm*

ubuntu/linux-ibm-5.15<5.15.0-1094.97~20.04.1

5.15.0-1094.97~20.04.1

ubuntu/linux-intel-5.13*

ubuntu/linux-intel-iotg-5.15<5.15.0-1095.101~20.04.1

5.15.0-1095.101~20.04.1

ubuntu/linux-iot*

ubuntu/linux-kvm*

ubuntu/linux-lowlatency-hwe-5.15<5.15.0-170.180~20.04.1

5.15.0-170.180~20.04.1

ubuntu/linux-nvidia-tegra-5.15<5.15.0-1052.52~20.04.2

5.15.0-1052.52~20.04.2

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<5.15.0-1097.103~20.04.1

5.15.0-1097.103~20.04.1

ubuntu/linux-oracle-5.8*

ubuntu/linux-raspi*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.11*

ubuntu/linux-riscv-5.15<5.15.0-1095.99~20.04.1

5.15.0-1095.99~20.04.1

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<5.15.0-170.180

5.15.0-170.180

ubuntu/linux-allwinner-5.19*

ubuntu/linux-aws<5.15.0-1100.107

5.15.0-1100.107

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<5.15.0-1109.118

5.15.0-1109.118

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<5.15.0-1109.118.1

5.15.0-1109.118.1

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<5.15.0-1100.109

5.15.0-1100.109

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<5.15.0-1096.102

5.15.0-1096.102

ubuntu/linux-gkeop<5.15.0-1083.91

5.15.0-1083.91

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<5.15.0-1094.97

5.15.0-1094.97

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<5.15.0-1095.101

5.15.0-1095.101

ubuntu/linux-kvm<5.15.0-1092.97

5.15.0-1092.97

ubuntu/linux-lowlatency<5.15.0-170.180

5.15.0-170.180

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<5.15.0-1095.96

5.15.0-1095.96

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<5.15.0-1052.52

5.15.0-1052.52

ubuntu/linux-nvidia-tegra-igx<5.15.0-1041.41

5.15.0-1041.41

ubuntu/linux-oem-5.17*

ubuntu/linux-oem-6.0*

ubuntu/linux-oem-6.1*

ubuntu/linux-oem-6.5*

ubuntu/linux-oracle<5.15.0-1097.103

5.15.0-1097.103

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<5.15.0-1097.100

5.15.0-1097.100

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<5.15.0-1064.68

5.15.0-1064.68

ubuntu/linux-bluefield<5.15.0-1084.86

5.15.0-1084.86

ubuntu/linux-intel-iot-realtime<5.15.0-1092.94

5.15.0-1092.94

ubuntu/linux-realtime<5.15.0-1099.108

5.15.0-1099.108

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<5.15.0-1100.107+fips1

5.15.0-1100.107+fips1

ubuntu/linux-azure-fips<5.15.0-1109.118+fips1

5.15.0-1109.118+fips1

ubuntu/linux-fips<5.15.0-170.180+fips1

5.15.0-170.180+fips1

ubuntu/linux-gcp-fips<5.15.0-1100.109+fips1

5.15.0-1100.109+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<6.8.0-1039.42

6.8.0-1039.42

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

ubuntu/linux-vmware*

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade ubuntu/linux-aws-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1100.107~20.04.2
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Fixed in 5.15.0-1110.119~20.04.1
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Fixed in 5.15.0-1100.109~20.04.1
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Fixed in 5.15.0-170.180~20.04.3
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Fixed in 5.15.0-1094.97~20.04.1
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Fixed in 5.15.0-1095.101~20.04.1
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Fixed in 5.15.0-170.180~20.04.1
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Fixed in 5.15.0-1052.52~20.04.2
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Fixed in 5.15.0-1097.103~20.04.1
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Fixed in 5.15.0-1095.99~20.04.1
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Fixed in 5.15.0-170.180
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Fixed in 5.15.0-1100.107
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Fixed in 6.8.0-1050.53~22.04.1
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Fixed in 5.15.0-1109.118
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Fixed in 6.8.0-1051.57~22.04.1
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Fixed in 5.15.0-1109.118.1
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Fixed in 6.8.0-1058.65~22.04.1
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Fixed in 5.15.0-1100.109
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Fixed in 6.8.0-1052.55~22.04.1
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Fixed in 5.15.0-1096.102
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Fixed in 5.15.0-1083.91
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Fixed in 6.8.0-106.106~22.04.1
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Fixed in 5.15.0-1094.97
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Fixed in 6.8.0-1049.49~22.04.1
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Fixed in 5.15.0-1095.101
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Fixed in 5.15.0-1092.97
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Fixed in 5.15.0-170.180
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Upgrade ubuntu/linux-lowlatency-hwe-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-106.106.1~22.04.1
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Fixed in 5.15.0-1095.96
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Fixed in 6.8.0-1049.52~22.04.1
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Fixed in 5.15.0-1052.52
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Fixed in 5.15.0-1041.41
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Fixed in 5.15.0-1097.103
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Fixed in 6.8.0-1047.48~22.04.1
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Fixed in 5.15.0-1097.100
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Fixed in 6.8.0-106.106~22.04.1
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Fixed in 5.15.0-1064.68
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Fixed in 5.15.0-1084.86
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Fixed in 5.15.0-1092.94
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Fixed in 5.15.0-1099.108
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Fixed in 6.8.1-1045.46~22.04.1
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Fixed in 5.15.0-1100.107+fips1
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Fixed in 5.15.0-1109.118+fips1
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Fixed in 5.15.0-170.180+fips1
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Fixed in 5.15.0-1100.109+fips1
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Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 6.8.0-106.106
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Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
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 6.8.0-1039.42
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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

Nov 12, 2025

CVE Published

via MITRE·09:56 PM

Data Sourced

via MITRE·09:56 PM

DescriptionSeverity

Data Sourced

via OSV·10:15 PM

DescriptionSeverityAffected Software

Data Sourced

via NVD·10:15 PM

DescriptionSeverity

Nov 14, 2025

Data Sourced

via Microsoft·01:03 AM

DescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

What is the severity of CVE-2025-40204?

CVE-2025-40204 has been classified as a moderate severity vulnerability due to its potential for timing attacks.

How do I fix CVE-2025-40204?

To resolve CVE-2025-40204, update your Linux kernel to the latest version where the issue has been addressed with constant-time MAC comparison.

What software is affected by CVE-2025-40204?

CVE-2025-40204 affects the Linux kernel, particularly versions prior to the fix being applied.

What type of attack does CVE-2025-40204 prevent?

CVE-2025-40204 prevents timing attacks by ensuring MAC comparisons are conducted in constant time.

Is CVE-2025-40204 still a risk if I update regularly?

CVE-2025-40204 is mitigated by updating to the patched version of the Linux kernel, reducing the risk significantly.

CVE-2025-40204: sctp: Fix MAC comparison to be constant-time

Affected Software

Remediation

Event History

Frequently Asked Questions

What is the severity of CVE-2025-40204?

How do I fix CVE-2025-40204?

What software is affected by CVE-2025-40204?

What type of attack does CVE-2025-40204 prevent?

Is CVE-2025-40204 still a risk if I update regularly?

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