CVE-2026-43384: net/tcp-ao: Fix MAC comparison to be constant-time

Q: Which systems are exposed to this issue?

Linux kernel systems using TCP Authentication Option (TCP-AO) are the relevant exposure area, because the affected code is in net/tcp-ao. The provided information does not identify specific kernel versions or whether TCP-AO is enabled by default.

Q: What does an attacker need to exploit it?

The issue is a timing side channel in TCP-AO MAC comparison. The supplied data indicates it can be exploited remotely without privileges or user interaction, but does not specify the traffic conditions or observations required to recover useful MAC information.

Q: How can I determine whether my system has the fix?

Check whether your kernel includes one of the referenced stable commits: 8be6ed64966da48b6c4726918f106c18742a5125, a269cbdc442f8658bca35383e34b9d0b0ff95a1c, or 080b0e210088296dd50d6637c06c1db14246adfe. These changes replace the MAC comparison with a constant-time comparison.

Published May 8, 2026

Updated

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

net/tcp-ao: 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

160 affected componentsFixes available

Linux Linux kernel

ubuntu/linux-hwe-edge*

ubuntu/linux-aws-5.0*

ubuntu/linux-aws-5.3*

ubuntu/linux-azure*

ubuntu/linux-azure-5.3*

ubuntu/linux-azure-edge*

ubuntu/linux-gcp*

ubuntu/linux-gcp-5.3*

ubuntu/linux-gke-4.15*

ubuntu/linux-gke-5.4*

ubuntu/linux-gkeop-5.4*

ubuntu/linux-hwe*

ubuntu/linux-hwe-edge*

ubuntu/linux-oem*

ubuntu/linux-oracle-5.0*

ubuntu/linux-oracle-5.3*

ubuntu/linux-aws-5.11*

ubuntu/linux-aws-5.13*

ubuntu/linux-aws-5.8*

ubuntu/linux-azure-5.11*

ubuntu/linux-azure-5.13*

ubuntu/linux-azure-5.8*

ubuntu/linux-azure-fde*

ubuntu/linux-gcp-5.11*

ubuntu/linux-gcp-5.13*

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-5.8*

ubuntu/linux-intel-5.13*

ubuntu/linux-oem-5.10*

ubuntu/linux-oem-5.13*

ubuntu/linux-oem-5.6*

ubuntu/linux-oracle-5.11*

ubuntu/linux-oracle-5.13*

ubuntu/linux-oracle-5.8*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.11*

ubuntu/linux-riscv-5.8*

ubuntu/linux-allwinner-5.19*

ubuntu/linux-aws-5.19*

ubuntu/linux-aws-6.2*

ubuntu/linux-aws-6.5*

ubuntu/linux-aws-6.8<6.8.0-1060.63~22.04.1

6.8.0-1060.63~22.04.1

ubuntu/linux-azure-5.19*

ubuntu/linux-azure-6.2*

ubuntu/linux-azure-6.5*

ubuntu/linux-azure-6.8<6.8.0-1063.71~22.04.1

6.8.0-1063.71~22.04.1

ubuntu/linux-azure-fde-5.19*

ubuntu/linux-azure-fde-6.2*

ubuntu/linux-azure-fde-6.8<6.8.0-1062.69~22.04.1

6.8.0-1062.69~22.04.1

ubuntu/linux-gcp-5.19*

ubuntu/linux-gcp-6.2*

ubuntu/linux-gcp-6.5*

ubuntu/linux-gcp-6.8<6.8.0-1063.69~22.04.1

6.8.0-1063.69~22.04.1

ubuntu/linux-hwe-5.19*

ubuntu/linux-hwe-6.2*

ubuntu/linux-hwe-6.5*

ubuntu/linux-hwe-6.8<6.8.0-136.136~22.04.1

6.8.0-136.136~22.04.1

ubuntu/linux-ibm-6.8<6.8.0-1060.61~22.04.1

6.8.0-1060.61~22.04.1

ubuntu/linux-intel-iot-realtime*

ubuntu/linux-lowlatency-hwe-5.19*

ubuntu/linux-lowlatency-hwe-6.2*

ubuntu/linux-lowlatency-hwe-6.5*

ubuntu/linux-lowlatency-hwe-6.8<6.8.0-134.134.1~22.04.1

6.8.0-134.134.1~22.04.1

ubuntu/linux-nvidia-6.2*

ubuntu/linux-nvidia-6.5*

ubuntu/linux-nvidia-6.8<6.8.0-1058.61~22.04.1

6.8.0-1058.61~22.04.1

ubuntu/linux-oem-5.17*

ubuntu/linux-oem-6.0*

ubuntu/linux-oem-6.1*

ubuntu/linux-oem-6.5*

ubuntu/linux-oracle-6.5*

ubuntu/linux-oracle-6.8<6.8.0-1057.58~22.04.1

6.8.0-1057.58~22.04.1

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.19*

ubuntu/linux-riscv-6.5*

ubuntu/linux-riscv-6.8<6.8.0-134.134~22.04.1

6.8.0-134.134~22.04.1

ubuntu/linux-starfive-5.19*

ubuntu/linux-starfive-6.2*

ubuntu/linux-starfive-6.5*

ubuntu/linux-realtime-6.8<6.8.1-1055.56~22.04.1

6.8.1-1055.56~22.04.1

ubuntu/linux<6.8.0-134.134

6.8.0-134.134

ubuntu/linux-aws<6.8.0-1060.63

6.8.0-1060.63

ubuntu/linux-aws-6.14*

ubuntu/linux-aws-6.17<6.17.0-1019.19~24.04.1

6.17.0-1019.19~24.04.1

ubuntu/linux-azure<6.8.0-1063.71

6.8.0-1063.71

ubuntu/linux-azure-6.11*

ubuntu/linux-azure-6.14*

ubuntu/linux-azure-6.17<6.17.0-1021.21~24.04.1

6.17.0-1021.21~24.04.1

ubuntu/linux-azure-fde<6.8.0-1062.69

6.8.0-1062.69

ubuntu/linux-azure-fde-6.14*

ubuntu/linux-azure-nvidia*

ubuntu/linux-azure-nvidia-6.14*

ubuntu/linux-gcp<6.8.0-1063.69

6.8.0-1063.69

ubuntu/linux-gcp-6.11*

ubuntu/linux-gcp-6.14*

ubuntu/linux-gcp-6.17<6.17.0-1020.22~24.04.1

6.17.0-1020.22~24.04.1

ubuntu/linux-gke<6.8.0-1058.64

6.8.0-1058.64

ubuntu/linux-gkeop<6.8.0-1045.48

6.8.0-1045.48

ubuntu/linux-hwe-6.11*

ubuntu/linux-hwe-6.14*

ubuntu/linux-hwe-6.17<6.17.0-40.40~24.04.1

6.17.0-40.40~24.04.1

ubuntu/linux-ibm<6.8.0-1060.61

6.8.0-1060.61

ubuntu/linux-lowlatency<6.8.0-134.134.1

6.8.0-134.134.1

ubuntu/linux-lowlatency-hwe-6.11*

ubuntu/linux-nvidia<6.8.0-1058.61

6.8.0-1058.61

ubuntu/linux-nvidia-6.11*

ubuntu/linux-nvidia-6.17<6.17.0-1026.26

6.17.0-1026.26

ubuntu/linux-nvidia-lowlatency<6.8.0-1058.61.1

6.8.0-1058.61.1

ubuntu/linux-nvidia-tegra<6.8.0-1029.30

6.8.0-1029.30

ubuntu/linux-oem-6.11*

ubuntu/linux-oem-6.14*

ubuntu/linux-oem-6.17<6.17.0-1028.28

6.17.0-1028.28

ubuntu/linux-oem-6.8*

ubuntu/linux-oracle<6.8.0-1057.58

6.8.0-1057.58

ubuntu/linux-oracle-6.14*

ubuntu/linux-oracle-6.17<6.17.0-1018.18~24.04.1

6.17.0-1018.18~24.04.1

ubuntu/linux-raspi<6.8.0-1060.64

6.8.0-1060.64

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-6.14*

ubuntu/linux-riscv-6.17*

ubuntu/linux-vmware<6.8.0-1008.8

6.8.0-1008.8

ubuntu/linux-xilinx<6.8.0-1032.33

6.8.0-1032.33

ubuntu/linux-bluefield<6.8.0-1026.30

6.8.0-1026.30

ubuntu/linux-raspi-realtime<6.8.0-2049.50

6.8.0-2049.50

ubuntu/linux-realtime<6.8.1-1055.56

6.8.1-1055.56

ubuntu/linux-realtime-6.14*

ubuntu/linux-realtime-6.17<6.17.0-1017.19~24.04.1

6.17.0-1017.19~24.04.1

ubuntu/linux-aws-fips<6.8.0-1060.63+fips1

6.8.0-1060.63+fips1

ubuntu/linux-azure-fips<6.8.0-1062.69+fips1

6.8.0-1062.69+fips1

ubuntu/linux-fips<6.8.0-134.134+fips1

6.8.0-134.134+fips1

ubuntu/linux-gcp-fips<6.8.0-1063.69+fips1

6.8.0-1063.69+fips1

ubuntu/linux<6.17.0-40.40

6.17.0-40.40

ubuntu/linux-aws<6.17.0-1019.19

6.17.0-1019.19

ubuntu/linux-azure*

ubuntu/linux-azure-fde*

ubuntu/linux-gcp<6.17.0-1020.22

6.17.0-1020.22

ubuntu/linux-oracle<6.17.0-1018.18

6.17.0-1018.18

ubuntu/linux-raspi<6.17.0-1021.21

6.17.0-1021.21

ubuntu/linux-realtime<6.17.0-1017.19

6.17.0-1017.19

ubuntu/linux-riscv<6.17.0-40.40.1

6.17.0-40.40.1

ubuntu/linux-vmware*

Linux Linux kernel>=6.7<6.12.78

Linux Linux kernel>=6.13<6.18.19

Linux Linux kernel>=6.19<6.19.9

Linux Linux kernel=7.0-rc1

Linux Linux kernel=7.0-rc2

debian/linux<6.12.85-1

6.12.85-1

debian/linux<6.19.10-1

6.19.10-1

debian/linux

6.1.176-16.1.190-16.12.107-16.12.116-17.2.15-17.3.4-1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade ubuntu/linux-aws-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1060.63~22.04.1
Upgrade
Upgrade ubuntu/linux-azure-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1063.71~22.04.1
Upgrade
Upgrade ubuntu/linux-azure-fde-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1062.69~22.04.1
Upgrade
Upgrade ubuntu/linux-gcp-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1063.69~22.04.1
Upgrade
Upgrade ubuntu/linux-hwe-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-136.136~22.04.1
Upgrade
Upgrade ubuntu/linux-ibm-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1060.61~22.04.1
Upgrade
Upgrade ubuntu/linux-lowlatency-hwe-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-134.134.1~22.04.1
Upgrade
Upgrade ubuntu/linux-nvidia-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1058.61~22.04.1
Upgrade
Upgrade ubuntu/linux-oracle-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1057.58~22.04.1
Upgrade
Upgrade ubuntu/linux-riscv-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-134.134~22.04.1
Upgrade
Upgrade ubuntu/linux-realtime-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.1-1055.56~22.04.1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 6.8.0-134.134
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 6.8.0-1060.63
Upgrade
Upgrade ubuntu/linux-aws-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1019.19~24.04.1
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 6.8.0-1063.71
Upgrade
Upgrade ubuntu/linux-azure-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1021.21~24.04.1
Upgrade
Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.
Fixed in 6.8.0-1062.69
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 6.8.0-1063.69
Upgrade
Upgrade ubuntu/linux-gcp-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1020.22~24.04.1
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 6.8.0-1058.64
Upgrade
Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.
Fixed in 6.8.0-1045.48
Upgrade
Upgrade ubuntu/linux-hwe-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-40.40~24.04.1
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 6.8.0-1060.61
Upgrade
Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-134.134.1
Upgrade
Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.
Fixed in 6.8.0-1058.61
Upgrade
Upgrade ubuntu/linux-nvidia-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1026.26
Upgrade
Upgrade ubuntu/linux-nvidia-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-1058.61.1
Upgrade
Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.
Fixed in 6.8.0-1029.30
Upgrade
Upgrade ubuntu/linux-oem-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1028.28
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 6.8.0-1057.58
Upgrade
Upgrade ubuntu/linux-oracle-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1018.18~24.04.1
Upgrade
Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.
Fixed in 6.8.0-1060.64
Upgrade
Upgrade ubuntu/linux-vmware to a version that resolves this vulnerability.
Fixed in 6.8.0-1008.8
Upgrade
Upgrade ubuntu/linux-xilinx to a version that resolves this vulnerability.
Fixed in 6.8.0-1032.33
Upgrade
Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.
Fixed in 6.8.0-1026.30
Upgrade
Upgrade ubuntu/linux-raspi-realtime to a version that resolves this vulnerability.
Fixed in 6.8.0-2049.50
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 6.8.1-1055.56
Upgrade
Upgrade ubuntu/linux-realtime-6.17 to a version that resolves this vulnerability.
Fixed in 6.17.0-1017.19~24.04.1
Upgrade
Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1060.63+fips1
Upgrade
Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1062.69+fips1
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-134.134+fips1
Upgrade
Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-1063.69+fips1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 6.17.0-40.40
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 6.17.0-1019.19
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 6.17.0-1020.22
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 6.17.0-1018.18
Upgrade
Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.
Fixed in 6.17.0-1021.21
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 6.17.0-1017.19
Upgrade
Upgrade ubuntu/linux-riscv to a version that resolves this vulnerability.
Fixed in 6.17.0-40.40.1

Event History

May 8, 2026

CVE Published

via MITRE·02:21 PM

Data Sourced

via MITRE·02:21 PM

DescriptionSeverity

Data Sourced

via OSV·03:16 PM

DescriptionSeverityAffected Software

Event

via OSV·03:16 PM

Data Sourced

via NVD·03:16 PM

RemedyDescriptionSeverityAffected Software

Frequently Asked Questions

Which systems are exposed to this issue?

Linux kernel systems using TCP Authentication Option (TCP-AO) are the relevant exposure area, because the affected code is in net/tcp-ao. The provided information does not identify specific kernel versions or whether TCP-AO is enabled by default.

What does an attacker need to exploit it?

The issue is a timing side channel in TCP-AO MAC comparison. The supplied data indicates it can be exploited remotely without privileges or user interaction, but does not specify the traffic conditions or observations required to recover useful MAC information.

How can I determine whether my system has the fix?

Check whether your kernel includes one of the referenced stable commits: 8be6ed64966da48b6c4726918f106c18742a5125, a269cbdc442f8658bca35383e34b9d0b0ff95a1c, or 080b0e210088296dd50d6637c06c1db14246adfe. These changes replace the MAC comparison with a constant-time comparison.

CVE-2026-43384: net/tcp-ao: Fix MAC comparison to be constant-time

Affected Software

Remediation

Event History

Frequently Asked Questions

Which systems are exposed to this issue?

What does an attacker need to exploit it?

How can I determine whether my system has the fix?

Company

Resources

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