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Vulnerability · Published Aug 12, 2026 · Assigned by Linux

CVE-2026-68431ksmbd: validate minimum PDU size for transform requests

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 31% 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 69.4% 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: validate minimum PDU size for transform requests The receive path applies the minimum SMB2 PDU size check only when ProtocolId is SMB2_PROTO_NUMBER. A packet carrying SMB2_TRANSFORM_PROTO_NUM bypasses the check even when the negotiated dialect does not provide transform handling. On an SMB 2.1 connection, a short transform packet therefore reaches init_smb2_rsp_hdr(), which interprets the request as a full SMB2 header and reads beyond the request allocation. The copied fields can then be returned to the unauthenticated client. Compression transforms are converted to ordinary SMB2 messages before protocol validation. After that conversion, validate ordinary SMB2 requests against SMB2_MIN_SUPPORTED_PDU_SIZE and require encryption transform requests to contain both a transform header and an SMB2 header. This rejects truncated requests before work allocation.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.187-1DEBIAN-CVE-2026-68431
Debian:13linux6.12.105-1DEBIAN-CVE-2026-68431
Debian:14linux7.1.6-1DEBIAN-CVE-2026-68431
Debian:12linux-6.126.12.107-1~deb12u1DEBIAN-CVE-2026-68431
Ubuntu:22.04:LTSlinux5.15.0-202.212UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinuxno fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux7.0.0-38.38UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-aws5.15.0-1119.126UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-awsno fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-aws7.0.0-1014.14UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-aws-6.17no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-aws-6.8no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-aws-7.07.0.0-1014.14~24.04.1UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-azure5.15.0-1125.134UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-azureno fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-azure7.0.0-1017.17UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-azure-6.17no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-azure-6.8no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-azure-7.07.0.0-1017.17~24.04.1UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1124.133UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-azure-fdeno fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-azure-fde7.0.0-1016.16UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-azure-fde-6.17no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-azure-fde-6.8no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-azure-fde-7.07.0.0-1016.16~24.04.1UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-gcp5.15.0-1120.130UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-gcpno fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-gcp7.0.0-1014.14UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-gcp-6.17no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-gcp-6.8no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-gcp-7.07.0.0-1014.14~24.04.1UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-gke5.15.0-1115.121UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-gkeno fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-gke7.0.0-1008.9UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1102.110UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-gkeopno fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-hwe-6.17no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-hwe-6.8no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-hwe-7.07.0.0-38.38~24.04.4UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-ibm5.15.0-1113.117UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-ibmno fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-ibm7.0.0-1015.15UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-ibm-6.8no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1114.120UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-kvm5.15.0-1111.116UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-197.207UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-lowlatencyno fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.8no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1114.115UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-nvidia-6.17no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-nvidia-6.8no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-nvidia-7.07.0.0-1024.25~24.04.1UBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-nvidia-bos7.0.0-2022.23UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-nvidia-lowlatencyno fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1070.72UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-nvidia-tegra6.8.0-1035.38UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1059.59UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-oem-6.17no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-oem-7.07.0.0-1015.15UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-oracle5.15.0-1116.122UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-oracleno fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-oracle7.0.0-1013.13UBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-oracle-6.17no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-oracle-6.8no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-oracle-7.07.0.0-1013.13~24.04.1UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-realtime7.0.0-38.38.1UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-68431
Ubuntu:26.04:LTSlinux-riscv7.0.0-38.38.1UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-riscv-6.8no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-riscv-7.07.0.0-38.38.1~24.04.1UBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-vmwareno fix listedUBUNTU-CVE-2026-68431
Ubuntu:24.04:LTSlinux-xilinxno fix listedUBUNTU-CVE-2026-68431
Ubuntu:22.04:LTSlinux-xilinx-zynqmpno fix listedUBUNTU-CVE-2026-68431

Affected products (as reported)

VendorProductVersions
Linux Linux df3a4518aee64f21bcafa891105b468413f27431 – before 22f1aa35b87e471cc31b35b74451f46630863b12543c12c2644e772caa6880662c2a852cfdc5a10c – before 928dda88d0e13fbca381255028f65b244343a4ea368ba06881c395f1c9a7ba22203cf8d78b4addc0 – before d8e5c5672724b8f3c4c099d2cf60239c996e5424368ba06881c395f1c9a7ba22203cf8d78b4addc0 – before 32e486b70c256d5ef4baa5a2936ade2fea50e8eb368ba06881c395f1c9a7ba22203cf8d78b4addc0 – before d9e9753dfd43bd27c956578df7804a3c90b80fdc368ba06881c395f1c9a7ba22203cf8d78b4addc0 – before b62c510f59803f82f9b4c76ead2a56833b2984c7368ba06881c395f1c9a7ba22203cf8d78b4addc0 – before cfc0b8e5080aec87700774e8568765eaa4b7b92be9cb7be2fcbaee9e808b729e92948d38d52e5add
Linux Linux 6.4

References