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Vulnerability · Published Aug 15, 2026 · Assigned by Linux

CVE-2026-74521ksmbd: use memcmp() to compare ClientGUIDs

Critical 9.1

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 0.4% (higher than 35% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.1Critical
Exploit odds (30 days)0.4%top 64.9% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: use memcmp() to compare ClientGUIDs ClientGUID is a fixed-size binary value and can contain embedded NUL bytes. strncmp() stops comparing at the first NUL byte, so different ClientGUID values can incorrectly be treated as equal. Use memcmp() in SMB3 multichannel session binding and FSCTL_VALIDATE_NEGOTIATE_INFO to compare all SMB2_CLIENT_GUID_SIZE bytes.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.190-1DEBIAN-CVE-2026-74521
Debian:13linux6.12.111-1DEBIAN-CVE-2026-74521
Debian:14linux7.1.8-1DEBIAN-CVE-2026-74521
Debian:12linux-6.126.12.111-1~deb12u1DEBIAN-CVE-2026-74521
Ubuntu:22.04:LTSlinuxno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinuxno fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux7.0.0-42.42UBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-awsno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-awsno fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-aws7.0.0-1016.17UBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-aws-6.17no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-aws-6.8no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-aws-7.0no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-azureno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-azureno fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-azureno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-azure-6.17no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-azure-6.8no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-azure-7.0no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-azure-fdeno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-azure-fdeno fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-azure-fdeno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-azure-fde-6.17no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-azure-fde-6.8no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-azure-fde-7.0no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-gcpno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-gcpno fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-gcp7.0.0-1016.18UBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-gcp-6.17no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-gcp-6.8no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-gcp-7.0no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-gkeno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-gkeno fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-gkeno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-gkeopno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-gkeopno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-hwe-6.17no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-hwe-6.8no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-hwe-7.07.0.0-42.42~24.04.1UBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-ibmno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-ibmno fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-ibm7.0.0-1017.17UBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-ibm-6.8no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-intel-iotgno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-kvmno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-lowlatencyno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-lowlatencyno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.8no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-nvidia-6.17no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-nvidia-6.8no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-nvidia-7.0no fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-nvidia-bosno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-nvidia-lowlatencyno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-nvidia-tegrano fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-nvidia-tegra6.8.0-1035.38UBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-nvidia-tegra-igxno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-oem-6.17no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-oem-7.07.0.0-1017.17UBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-oracleno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-oracleno fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-oracle7.0.0-1015.16UBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-oracle-6.17no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-oracle-6.8no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-oracle-7.0no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-74521
Ubuntu:26.04:LTSlinux-riscv7.0.0-42.42.1UBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-riscv-6.8no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-riscv-7.07.0.0-42.42.1~24.04.1UBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-vmwareno fix listedUBUNTU-CVE-2026-74521
Ubuntu:24.04:LTSlinux-xilinxno fix listedUBUNTU-CVE-2026-74521
Ubuntu:22.04:LTSlinux-xilinx-zynqmpno fix listedUBUNTU-CVE-2026-74521

Affected products (as reported)

VendorProductVersions
Linux Linux e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 – before 7bde6f181fa307d2cc1ec2b0313ac8e9811c8232e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 – before 5a0367bf5ce420be7b19936def2e90adcf32a683e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 – before ba2a5b66f1d414eb8403d655f8813783892cfc85e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 – before a386c83043015a703e227775f778e40343f45911e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 – before d535363299822c5caa543787b21bd5cfa3e41949e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 – before e8bb506e6ef749ac0336f3e579d8d02396b7d832
Linux Linux 5.15

References