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Vulnerability · Published May 8, 2026 · Assigned by Linux

CVE-2026-43383net/tcp-md5: Fix MAC comparison to be constant-time

Critical 9.4

In plain English

A critical-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 46% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.4Critical
Exploit odds (30 days)0.5%top 54.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

In the Linux kernel, the following vulnerability has been resolved: net/tcp-md5: 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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.170-1DEBIAN-CVE-2026-43383
Debian:13linux6.12.85-1DEBIAN-CVE-2026-43383
Debian:14linux6.19.10-1DEBIAN-CVE-2026-43383
Ubuntu:22.04:LTSlinux5.15.0-185.195UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux6.8.0-134.134UBUNTU-CVE-2026-43383
Ubuntu:25.10linux6.17.0-40.40UBUNTU-CVE-2026-43383
Ubuntu:25.10linux6.17.0-40.40USN-8490-1
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-aws5.15.0-1111.118UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-aws6.8.0-1060.63UBUNTU-CVE-2026-43383
Ubuntu:25.10linux-aws6.17.0-1019.19USN-8490-1
Ubuntu:25.10linux-aws6.17.0-1019.19UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-aws-6.176.17.0-1019.19~24.04.1UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-aws-6.176.17.0-1019.19~24.04.1USN-8490-1
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-aws-6.86.8.0-1060.63~22.04.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-azure5.15.0-1116.125UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-azure6.8.0-1063.71UBUNTU-CVE-2026-43383
Ubuntu:25.10linux-azureno fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-azure-6.176.17.0-1021.21~24.04.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-azure-6.86.8.0-1063.71~22.04.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1116.125UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-azure-fde6.8.0-1062.69UBUNTU-CVE-2026-43383
Ubuntu:25.10linux-azure-fdeno fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-azure-fde-6.86.8.0-1062.69~22.04.1UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-gcp5.15.0-1111.121UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-gcp6.8.0-1063.69UBUNTU-CVE-2026-43383
Ubuntu:25.10linux-gcp6.17.0-1020.22UBUNTU-CVE-2026-43383
Ubuntu:25.10linux-gcp6.17.0-1020.22USN-8490-1
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-gcp-6.176.17.0-1020.22~24.04.1UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-gcp-6.176.17.0-1020.22~24.04.1USN-8490-1
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-gcp-6.86.8.0-1063.69~22.04.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-gke5.15.0-1107.113UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-gke6.8.0-1058.64UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1094.102UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-gkeop6.8.0-1045.48UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-hwe-6.176.17.0-40.40~24.04.1UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-hwe-6.176.17.0-40.40~24.04.1USN-8545-1
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-hwe-6.86.8.0-136.136~22.04.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-ibm5.15.0-1105.109UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-ibm6.8.0-1060.61UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-ibm-6.86.8.0-1060.61~22.04.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1106.112UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-kvm5.15.0-1103.108UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-183.193UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-lowlatency6.8.0-134.134.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.86.8.0-134.134.1~22.04.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1106.107UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-nvidia6.8.0-1058.61UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-nvidia-6.176.17.0-1026.26UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-nvidia-6.86.8.0-1058.61~22.04.1UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-nvidia-lowlatency6.8.0-1058.61.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1063.63UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-nvidia-tegra6.8.0-1029.30UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1052.52UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-oem-6.176.17.0-1028.28USN-8491-1
Ubuntu:24.04:LTSlinux-oem-6.176.17.0-1028.28UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-oracle5.15.0-1108.114UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-oracle6.8.0-1057.58UBUNTU-CVE-2026-43383
Ubuntu:25.10linux-oracle6.17.0-1018.18UBUNTU-CVE-2026-43383
Ubuntu:25.10linux-oracle6.17.0-1018.18USN-8490-1
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-oracle-6.176.17.0-1018.18~24.04.1USN-8490-1
Ubuntu:24.04:LTSlinux-oracle-6.176.17.0-1018.18~24.04.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-oracle-6.86.8.0-1057.58~22.04.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-raspi5.15.0-1105.108UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-raspi6.8.0-1060.64UBUNTU-CVE-2026-43383
Ubuntu:25.10linux-raspi6.17.0-1021.21USN-8546-1
Ubuntu:25.10linux-raspi6.17.0-1021.21UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-43383
Ubuntu:25.10linux-realtime6.17.0-1017.19USN-8490-2
Ubuntu:25.10linux-realtime6.17.0-1017.19UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-43383
Ubuntu:25.10linux-riscv6.17.0-40.40.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-riscv-6.86.8.0-134.134~22.04.1UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-vmware6.8.0-1008.8UBUNTU-CVE-2026-43383
Ubuntu:24.04:LTSlinux-xilinx6.8.0-1032.33UBUNTU-CVE-2026-43383
Ubuntu:22.04:LTSlinux-xilinx-zynqmp5.15.0-1074.78UBUNTU-CVE-2026-43383

Affected products (as reported)

VendorProductVersions
Linux Linux cfb6eeb4c860592edd123fdea908d23c6ad1c7dc – before 821c8751fdeecdeecabeb11704dd33439c9e4bbccfb6eeb4c860592edd123fdea908d23c6ad1c7dc – before ff44ec94d4fc8348600a69de0a8fa1102c23bce8cfb6eeb4c860592edd123fdea908d23c6ad1c7dc – before 345a9530756528d7ca407663d659c3c40e75c3ddcfb6eeb4c860592edd123fdea908d23c6ad1c7dc – before 5d305a95130a8d08b9545e47f1e18d29d59866cbcfb6eeb4c860592edd123fdea908d23c6ad1c7dc – before 02669e2a4d207068edce7e8b5fafd85822018ce6cfb6eeb4c860592edd123fdea908d23c6ad1c7dc – before ae3831b44f477de048287493e184fc3ff913b624cfb6eeb4c860592edd123fdea908d23c6ad1c7dc – before b502e97e29d791ff7a8051f29a414535739be218cfb6eeb4c860592edd123fdea908d23c6ad1c7dc – before 46d0d6f50dab706637f4c18a470aac20a21900d3
Linux Linux 2.6.20

Weakness: CWE-208 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H

References