Vulnerabilities
Misconfiguration
Compliance
CVE Vulnerabilities

CVE-2026-63909

Published: Jul 19, 2026 | Modified: Jul 20, 2026
CVSS 3.x
N/A
Source:
NVD
CVSS 2.x
RedHat/V2
RedHat/V3
Ubuntu
MEDIUM
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2026-63909
CWEhttps://cwe.mitre.org/data/definitions/.html

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

ksmbd: OOB read regression in smb_check_perm_dacl() ACE-walk loops

Commit d07b26f39246 (ksmbd: require minimum ACE size in smb_check_perm_dacl()) introduced a transposed bounds check:

if (offsetof(struct smb_ace, sid) + aces_size < CIFS_SID_BASE_SIZE)

Since offsetof(..sid) is 8 and CIFS_SID_BASE_SIZE is 8, this evaluates to aces_size < 0. Because aces_size is always non-negative, this check becomes dead code and never breaks the loop.

Worse, that commit removed the old 4-byte guard, meaning the loop now reads ace->size (offset 2) even when aces_size is 0-3 bytes. This re-opens a 2-byte heap out-of-bounds (OOB) read past the pntsd allocation during subsequent SMB2_CREATE operations.

Fix this by properly transposing the comparison to require at least 16 bytes (8-byte offset + 8-byte SID base), matching the correct form used in smb_inherit_dacl().

Affected Software

NameVendorStart VersionEnd Version
LinuxUbuntunoble*
LinuxUbunturesolute*
LinuxUbuntuupstream*
Linux-allwinner-5.19Ubuntujammy*
Linux-allwinner-5.19Ubuntuupstream*
Linux-awsUbuntunoble*
Linux-awsUbunturesolute*
Linux-awsUbuntuupstream*
Linux-aws-5.0Ubuntubionic*
Linux-aws-5.0Ubuntuesm-infra/bionic*
Linux-aws-5.0Ubuntuupstream*
Linux-aws-5.11Ubuntuesm-infra/focal*
Linux-aws-5.11Ubuntufocal*
Linux-aws-5.11Ubuntuupstream*
Linux-aws-5.13Ubuntuesm-infra/focal*
Linux-aws-5.13Ubuntufocal*
Linux-aws-5.13Ubuntuupstream*
Linux-aws-5.15Ubuntuupstream*
Linux-aws-5.19Ubuntujammy*
Linux-aws-5.19Ubuntuupstream*
Linux-aws-5.3Ubuntubionic*
Linux-aws-5.3Ubuntuesm-infra/bionic*
Linux-aws-5.3Ubuntuupstream*
Linux-aws-5.4Ubuntuupstream*
Linux-aws-5.8Ubuntuesm-infra/focal*
Linux-aws-5.8Ubuntufocal*
Linux-aws-5.8Ubuntuupstream*
Linux-aws-6.14Ubuntunoble*
Linux-aws-6.14Ubuntuupstream*
Linux-aws-6.17Ubuntunoble*
Linux-aws-6.17Ubuntuupstream*
Linux-aws-6.2Ubuntujammy*
Linux-aws-6.2Ubuntuupstream*
Linux-aws-6.5Ubuntujammy*
Linux-aws-6.5Ubuntuupstream*
Linux-aws-6.8Ubuntujammy*
Linux-aws-6.8Ubuntuupstream*
Linux-aws-fipsUbuntufips-updates/noble*
Linux-aws-fipsUbuntuupstream*
Linux-aws-hweUbuntuupstream*
Linux-azureUbuntubionic*
Linux-azureUbuntuesm-infra/bionic*
Linux-azureUbuntunoble*
Linux-azureUbunturesolute*
Linux-azureUbuntuupstream*
Linux-azure-4.15Ubuntuupstream*
Linux-azure-5.11Ubuntuesm-infra/focal*
Linux-azure-5.11Ubuntufocal*
Linux-azure-5.11Ubuntuupstream*
Linux-azure-5.13Ubuntuesm-infra/focal*
Linux-azure-5.13Ubuntufocal*
Linux-azure-5.13Ubuntuupstream*
Linux-azure-5.15Ubuntuupstream*
Linux-azure-5.19Ubuntujammy*
Linux-azure-5.19Ubuntuupstream*
Linux-azure-5.3Ubuntubionic*
Linux-azure-5.3Ubuntuesm-infra/bionic*
Linux-azure-5.3Ubuntuupstream*
Linux-azure-5.4Ubuntuupstream*
Linux-azure-5.8Ubuntuesm-infra/focal*
Linux-azure-5.8Ubuntufocal*
Linux-azure-5.8Ubuntuupstream*
Linux-azure-6.11Ubuntunoble*
Linux-azure-6.11Ubuntuupstream*
Linux-azure-6.14Ubuntunoble*
Linux-azure-6.14Ubuntuupstream*
Linux-azure-6.17Ubuntuupstream*
Linux-azure-6.2Ubuntujammy*
Linux-azure-6.2Ubuntuupstream*
Linux-azure-6.5Ubuntujammy*
Linux-azure-6.5Ubuntuupstream*
Linux-azure-6.8Ubuntujammy*
Linux-azure-6.8Ubuntuupstream*
Linux-azure-edgeUbuntubionic*
Linux-azure-edgeUbuntuesm-infra/bionic*
Linux-azure-edgeUbuntuupstream*
Linux-azure-fdeUbuntudevel*
Linux-azure-fdeUbuntuesm-infra/focal*
Linux-azure-fdeUbuntufocal*
Linux-azure-fdeUbuntunoble*
Linux-azure-fdeUbuntuupstream*
Linux-azure-fde-5.15Ubuntuupstream*
Linux-azure-fde-5.19Ubuntujammy*
Linux-azure-fde-5.19Ubuntuupstream*
Linux-azure-fde-6.14Ubuntunoble*
Linux-azure-fde-6.14Ubuntuupstream*
Linux-azure-fde-6.17Ubuntuupstream*
Linux-azure-fde-6.2Ubuntujammy*
Linux-azure-fde-6.2Ubuntuupstream*
Linux-azure-fde-6.8Ubuntujammy*
Linux-azure-fde-6.8Ubuntuupstream*
Linux-azure-fipsUbuntufips-updates/noble*
Linux-azure-fipsUbuntuupstream*
Linux-azure-nvidiaUbuntunoble*
Linux-azure-nvidiaUbuntuupstream*
Linux-azure-nvidia-6.14Ubuntunoble*
Linux-azure-nvidia-6.14Ubuntuupstream*
Linux-bluefieldUbuntuupstream*
Linux-fipsUbuntufips-updates/noble*
Linux-fipsUbuntuupstream*
Linux-gcpUbuntubionic*
Linux-gcpUbuntuesm-infra/bionic*
Linux-gcpUbuntunoble*
Linux-gcpUbunturesolute*
Linux-gcpUbuntuupstream*
Linux-gcp-4.15Ubuntuupstream*
Linux-gcp-5.11Ubuntuesm-infra/focal*
Linux-gcp-5.11Ubuntufocal*
Linux-gcp-5.11Ubuntuupstream*
Linux-gcp-5.13Ubuntuesm-infra/focal*
Linux-gcp-5.13Ubuntufocal*
Linux-gcp-5.13Ubuntuupstream*
Linux-gcp-5.15Ubuntuupstream*
Linux-gcp-5.19Ubuntujammy*
Linux-gcp-5.19Ubuntuupstream*
Linux-gcp-5.3Ubuntubionic*
Linux-gcp-5.3Ubuntuesm-infra/bionic*
Linux-gcp-5.3Ubuntuupstream*
Linux-gcp-5.4Ubuntuupstream*
Linux-gcp-5.8Ubuntuesm-infra/focal*
Linux-gcp-5.8Ubuntufocal*
Linux-gcp-5.8Ubuntuupstream*
Linux-gcp-6.11Ubuntunoble*
Linux-gcp-6.11Ubuntuupstream*
Linux-gcp-6.14Ubuntunoble*
Linux-gcp-6.14Ubuntuupstream*
Linux-gcp-6.17Ubuntuupstream*
Linux-gcp-6.2Ubuntujammy*
Linux-gcp-6.2Ubuntuupstream*
Linux-gcp-6.5Ubuntujammy*
Linux-gcp-6.5Ubuntuupstream*
Linux-gcp-6.8Ubuntujammy*
Linux-gcp-6.8Ubuntuupstream*
Linux-gcp-fipsUbuntufips-updates/noble*
Linux-gcp-fipsUbuntuupstream*
Linux-gkeUbuntuesm-infra/focal*
Linux-gkeUbuntufocal*
Linux-gkeUbuntunoble*
Linux-gkeUbunturesolute*
Linux-gkeUbuntuupstream*
Linux-gkeUbuntuxenial*
Linux-gke-4.15Ubuntubionic*
Linux-gke-4.15Ubuntuesm-infra/bionic*
Linux-gke-4.15Ubuntuupstream*
Linux-gke-5.15Ubuntuesm-infra/focal*
Linux-gke-5.15Ubuntufocal*
Linux-gke-5.15Ubuntuupstream*
Linux-gke-5.4Ubuntubionic*
Linux-gke-5.4Ubuntuesm-infra/bionic*
Linux-gke-5.4Ubuntuupstream*
Linux-gkeopUbuntuesm-infra/focal*
Linux-gkeopUbuntufocal*
Linux-gkeopUbuntunoble*
Linux-gkeopUbuntuupstream*
Linux-gkeop-5.15Ubuntuesm-infra/focal*
Linux-gkeop-5.15Ubuntufocal*
Linux-gkeop-5.15Ubuntuupstream*
Linux-gkeop-5.4Ubuntubionic*
Linux-gkeop-5.4Ubuntuesm-infra/bionic*
Linux-gkeop-5.4Ubuntuupstream*
Linux-hweUbuntubionic*
Linux-hweUbuntuesm-infra/bionic*
Linux-hweUbuntuupstream*
Linux-hwe-5.11Ubuntuesm-infra/focal*
Linux-hwe-5.11Ubuntufocal*
Linux-hwe-5.11Ubuntuupstream*
Linux-hwe-5.13Ubuntuesm-infra/focal*
Linux-hwe-5.13Ubuntufocal*
Linux-hwe-5.13Ubuntuupstream*
Linux-hwe-5.15Ubuntuupstream*
Linux-hwe-5.19Ubuntujammy*
Linux-hwe-5.19Ubuntuupstream*
Linux-hwe-5.4Ubuntuupstream*
Linux-hwe-5.8Ubuntuesm-infra/focal*
Linux-hwe-5.8Ubuntufocal*
Linux-hwe-5.8Ubuntuupstream*
Linux-hwe-6.11Ubuntunoble*
Linux-hwe-6.11Ubuntuupstream*
Linux-hwe-6.14Ubuntunoble*
Linux-hwe-6.14Ubuntuupstream*
Linux-hwe-6.17Ubuntuupstream*
Linux-hwe-6.2Ubuntujammy*
Linux-hwe-6.2Ubuntuupstream*
Linux-hwe-6.5Ubuntujammy*
Linux-hwe-6.5Ubuntuupstream*
Linux-hwe-6.8Ubuntujammy*
Linux-hwe-6.8Ubuntuupstream*
Linux-hwe-7.0Ubuntuupstream*
Linux-hwe-edgeUbuntubionic*
Linux-hwe-edgeUbuntuesm-infra-legacy/xenial*
Linux-hwe-edgeUbuntuesm-infra/bionic*
Linux-hwe-edgeUbuntuesm-infra/xenial*
Linux-hwe-edgeUbuntuupstream*
Linux-hwe-edgeUbuntuxenial*
Linux-ibmUbuntunoble*
Linux-ibmUbunturesolute*
Linux-ibmUbuntuupstream*
Linux-ibm-5.15Ubuntuupstream*
Linux-ibm-5.4Ubuntuupstream*
Linux-ibm-6.8Ubuntujammy*
Linux-ibm-6.8Ubuntuupstream*
Linux-intel-5.13Ubuntuesm-infra/focal*
Linux-intel-5.13Ubuntufocal*
Linux-intel-5.13Ubuntuupstream*
Linux-intel-iot-realtimeUbuntujammy*
Linux-intel-iot-realtimeUbuntuupstream*
Linux-intel-iotgUbuntuupstream*
Linux-intel-iotg-5.15Ubuntuupstream*
Linux-iotUbuntuupstream*
Linux-kvmUbuntuupstream*
Linux-lowlatencyUbuntunoble*
Linux-lowlatencyUbuntuupstream*
Linux-lowlatency-hwe-5.15Ubuntuupstream*
Linux-lowlatency-hwe-5.19Ubuntujammy*
Linux-lowlatency-hwe-5.19Ubuntuupstream*
Linux-lowlatency-hwe-6.11Ubuntunoble*
Linux-lowlatency-hwe-6.11Ubuntuupstream*
Linux-lowlatency-hwe-6.2Ubuntujammy*
Linux-lowlatency-hwe-6.2Ubuntuupstream*
Linux-lowlatency-hwe-6.5Ubuntujammy*
Linux-lowlatency-hwe-6.5Ubuntuupstream*
Linux-lowlatency-hwe-6.8Ubuntujammy*
Linux-lowlatency-hwe-6.8Ubuntuupstream*
Linux-lts-xenialUbuntuupstream*
Linux-nvidiaUbuntunoble*
Linux-nvidiaUbunturesolute*
Linux-nvidiaUbuntuupstream*
Linux-nvidia-6.11Ubuntunoble*
Linux-nvidia-6.11Ubuntuupstream*
Linux-nvidia-6.17Ubuntuupstream*
Linux-nvidia-6.2Ubuntujammy*
Linux-nvidia-6.2Ubuntuupstream*
Linux-nvidia-6.5Ubuntujammy*
Linux-nvidia-6.5Ubuntuupstream*
Linux-nvidia-6.8Ubuntujammy*
Linux-nvidia-6.8Ubuntuupstream*
Linux-nvidia-7.0Ubuntunoble*
Linux-nvidia-7.0Ubuntuupstream*
Linux-nvidia-bosUbunturesolute*
Linux-nvidia-bosUbuntuupstream*
Linux-nvidia-lowlatencyUbuntunoble*
Linux-nvidia-lowlatencyUbuntuupstream*
Linux-nvidia-tegraUbuntunoble*
Linux-nvidia-tegraUbuntuupstream*
Linux-nvidia-tegra-5.15Ubuntuupstream*
Linux-nvidia-tegra-igxUbuntuupstream*
Linux-oemUbuntubionic*
Linux-oemUbuntuesm-infra/bionic*
Linux-oemUbuntuupstream*
Linux-oemUbuntuxenial*
Linux-oem-5.10Ubuntuesm-infra/focal*
Linux-oem-5.10Ubuntufocal*
Linux-oem-5.10Ubuntuupstream*
Linux-oem-5.13Ubuntuesm-infra/focal*
Linux-oem-5.13Ubuntufocal*
Linux-oem-5.13Ubuntuupstream*
Linux-oem-5.14Ubuntuesm-infra/focal*
Linux-oem-5.14Ubuntufocal*
Linux-oem-5.14Ubuntuupstream*
Linux-oem-5.17Ubuntujammy*
Linux-oem-5.17Ubuntuupstream*
Linux-oem-5.6Ubuntuesm-infra/focal*
Linux-oem-5.6Ubuntufocal*
Linux-oem-5.6Ubuntuupstream*
Linux-oem-6.0Ubuntujammy*
Linux-oem-6.0Ubuntuupstream*
Linux-oem-6.1Ubuntujammy*
Linux-oem-6.1Ubuntuupstream*
Linux-oem-6.11Ubuntunoble*
Linux-oem-6.11Ubuntuupstream*
Linux-oem-6.14Ubuntunoble*
Linux-oem-6.14Ubuntuupstream*
Linux-oem-6.17Ubuntuupstream*
Linux-oem-6.5Ubuntujammy*
Linux-oem-6.5Ubuntuupstream*
Linux-oem-6.8Ubuntunoble*
Linux-oem-6.8Ubuntuupstream*
Linux-oem-7.0Ubunturesolute*
Linux-oem-7.0Ubuntuupstream*
Linux-oracleUbuntunoble*
Linux-oracleUbunturesolute*
Linux-oracleUbuntuupstream*
Linux-oracle-5.0Ubuntubionic*
Linux-oracle-5.0Ubuntuesm-infra/bionic*
Linux-oracle-5.0Ubuntuupstream*
Linux-oracle-5.11Ubuntuesm-infra/focal*
Linux-oracle-5.11Ubuntufocal*
Linux-oracle-5.11Ubuntuupstream*
Linux-oracle-5.13Ubuntuesm-infra/focal*
Linux-oracle-5.13Ubuntufocal*
Linux-oracle-5.13Ubuntuupstream*
Linux-oracle-5.15Ubuntuupstream*
Linux-oracle-5.3Ubuntubionic*
Linux-oracle-5.3Ubuntuesm-infra/bionic*
Linux-oracle-5.3Ubuntuupstream*
Linux-oracle-5.4Ubuntuupstream*
Linux-oracle-5.8Ubuntuesm-infra/focal*
Linux-oracle-5.8Ubuntufocal*
Linux-oracle-5.8Ubuntuupstream*
Linux-oracle-6.14Ubuntunoble*
Linux-oracle-6.14Ubuntuupstream*
Linux-oracle-6.17Ubuntuupstream*
Linux-oracle-6.5Ubuntujammy*
Linux-oracle-6.5Ubuntuupstream*
Linux-oracle-6.8Ubuntujammy*
Linux-oracle-6.8Ubuntuupstream*
Linux-raspiUbuntudevel*
Linux-raspiUbuntunoble*
Linux-raspiUbunturesolute*
Linux-raspiUbuntuupstream*
Linux-raspi-5.4Ubuntuupstream*
Linux-raspi-realtimeUbuntunoble*
Linux-raspi-realtimeUbunturealtime/noble*
Linux-raspi-realtimeUbuntuupstream*
Linux-raspi2Ubuntubionic*
Linux-raspi2Ubuntuesm-infra/focal*
Linux-raspi2Ubuntufocal*
Linux-raspi2Ubuntuupstream*
Linux-raspi2Ubuntuxenial*
Linux-realtimeUbuntujammy*
Linux-realtimeUbuntunoble*
Linux-realtimeUbunturealtime/noble*
Linux-realtimeUbunturesolute*
Linux-realtimeUbuntuupstream*
Linux-realtime-6.14Ubunturealtime/noble*
Linux-realtime-6.14Ubuntuupstream*
Linux-realtime-6.17Ubuntuupstream*
Linux-realtime-6.8Ubunturealtime/jammy*
Linux-realtime-6.8Ubuntuupstream*
Linux-riscvUbuntuesm-infra/focal*
Linux-riscvUbuntufocal*
Linux-riscvUbuntujammy*
Linux-riscvUbuntunoble*
Linux-riscvUbunturesolute*
Linux-riscvUbuntuupstream*
Linux-riscv-5.11Ubuntuesm-infra/focal*
Linux-riscv-5.11Ubuntufocal*
Linux-riscv-5.11Ubuntuupstream*
Linux-riscv-5.15Ubuntuupstream*
Linux-riscv-5.19Ubuntujammy*
Linux-riscv-5.19Ubuntuupstream*
Linux-riscv-5.8Ubuntuesm-infra/focal*
Linux-riscv-5.8Ubuntufocal*
Linux-riscv-5.8Ubuntuupstream*
Linux-riscv-6.14Ubuntunoble*
Linux-riscv-6.14Ubuntuupstream*
Linux-riscv-6.17Ubuntunoble*
Linux-riscv-6.17Ubuntuupstream*
Linux-riscv-6.5Ubuntujammy*
Linux-riscv-6.5Ubuntuupstream*
Linux-riscv-6.8Ubuntujammy*
Linux-riscv-6.8Ubuntuupstream*
Linux-starfive-5.19Ubuntujammy*
Linux-starfive-5.19Ubuntuupstream*
Linux-starfive-6.2Ubuntujammy*
Linux-starfive-6.2Ubuntuupstream*
Linux-starfive-6.5Ubuntujammy*
Linux-starfive-6.5Ubuntuupstream*
Linux-xilinxUbuntunoble*
Linux-xilinxUbuntuupstream*
Linux-xilinx-zynqmpUbuntuupstream*

References

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