Out-of-bounds read in Linux kernel - CVE-2026-64578

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Main Vulnerability Database Vulnerabilities #VU141030

Out-of-bounds read in Linux kernel - CVE-2026-64578

Published: August 6, 2026


Vulnerability identifier: #VU141030
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64578
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to disclose sensitive information.

The vulnerability exists due to an out-of-bounds read in ksmbd_smb2_check_message() when processing a crafted compound SMB2 request. A remote attacker can send a specially crafted compound request with a trailing element that is too small to hold StructureSize2 to disclose sensitive information.

The issue occurs when the last compound element contains only a 64-byte SMB2 header, causing a 2-byte read at offset 64 to extend past the receive buffer.


Affected software

Linux kernel
Debian Linux
Ubuntu
linux (Ubuntu package)
linux-kvm (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-azure (Ubuntu package)
linux-oracle (Ubuntu package)
linux-lowlatency (Ubuntu package)
linux-gke (Ubuntu package)
linux-aws-5.15 (Ubuntu package)
linux-lowlatency-hwe-5.15 (Ubuntu package)
linux-hwe-5.15 (Ubuntu package)
linux-fips (Ubuntu package)
linux-azure-5.15 (Ubuntu package)
linux-azure-fde-5.15 (Ubuntu package)
linux-nvidia-tegra (Ubuntu package)
linux-ibm-5.15 (Ubuntu package)
linux-realtime (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-gkeop (Ubuntu package)
linux-nvidia-tegra-igx (Ubuntu package)
linux-intel-iotg (Ubuntu package)
linux-ibm (Ubuntu package)
linux-intel-iotg-5.15 (Ubuntu package)
linux-oracle-5.15 (Ubuntu package)
linux-gcp-5.15 (Ubuntu package)
linux-nvidia-tegra-5.15 (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux-xilinx-zynqmp (Ubuntu package)
linux-intel-iot-realtime (Ubuntu package)
linux-gcp-fips (Ubuntu package)
linux-aws-fips (Ubuntu package)
linux-azure-fips (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux (Debian package)
linux-azure-7.0 (Ubuntu package)

How to mitigate CVE-2026-64578

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 5.15.0-198.208, 6.8.0-147.147, 7.0.0-38.38
linux-kvm (Ubuntu package) - update to 5.15.0-1109.114
linux-aws (Ubuntu package) - addressed in versions 5.15.0-1117.124, 6.8.0-1067.70, 7.0.0-1014.14
linux-gcp (Ubuntu package) - addressed in versions 5.15.0-1118.128, 6.8.0-1071.79, 7.0.0-1014.14
linux-azure (Ubuntu package) - addressed in versions 5.15.0-1123.132, 6.8.0-1071.79, 7.0.0-1016.16, 7.0.0-1017.17
linux-oracle (Ubuntu package) - addressed in versions 5.15.0-1114.120, 6.8.0-1064.67, 7.0.0-1013.13
linux-lowlatency (Ubuntu package) - addressed in versions 5.15.0-195.205, 6.8.0-147.147.1
linux-gke (Ubuntu package) - addressed in versions 5.15.0-1113.119, 6.8.0-1066.74, 7.0.0-1008.9
linux-aws-5.15 (Ubuntu package) - update to 5.15.0-1117.124~20.04.1
linux-lowlatency-hwe-5.15 (Ubuntu package) - update to 5.15.0-195.205~20.04.1
linux-hwe-5.15 (Ubuntu package) - update to 5.15.0-198.208~20.04.1
linux-fips (Ubuntu package) - addressed in versions 5.15.0-198.208+fips1, 6.8.0-147.147+fips1
linux-azure-5.15 (Ubuntu package) - update to 5.15.0-1123.132~20.04.1
linux-azure-fde-5.15 (Ubuntu package) - update to 5.15.0-1122.131~20.04.1
linux-nvidia-tegra (Ubuntu package) - addressed in versions 5.15.0-1070.72, 6.8.0-1036.39
linux-ibm-5.15 (Ubuntu package) - update to 5.15.0-1111.115~20.04.1
linux-realtime (Ubuntu package) - addressed in versions 5.15.0-1116.125, 6.8.1-1062.63, 7.0.0-38.38.1
linux-nvidia (Ubuntu package) - update to 5.15.0-1112.113
linux-gkeop (Ubuntu package) - addressed in versions 5.15.0-1100.108, 6.8.0-1052.56
linux-nvidia-tegra-igx (Ubuntu package) - update to 5.15.0-1059.59
linux-intel-iotg (Ubuntu package) - update to 5.15.0-1112.118
linux-ibm (Ubuntu package) - addressed in versions 5.15.0-1111.115, 6.8.0-1067.68, 7.0.0-1015.15
linux-intel-iotg-5.15 (Ubuntu package) - update to 5.15.0-1112.118~20.04.1
linux-oracle-5.15 (Ubuntu package) - update to 5.15.0-1114.120~20.04.1
linux-gcp-5.15 (Ubuntu package) - update to 5.15.0-1118.128~20.04.1
linux-nvidia-tegra-5.15 (Ubuntu package) - update to 5.15.0-1070.72~20.04.1
linux-azure-fde (Ubuntu package) - addressed in versions 5.15.0-1122.131, 6.8.0-1069.76
linux-xilinx-zynqmp (Ubuntu package) - update to 5.15.0-1080.84
linux-intel-iot-realtime (Ubuntu package) - update to 5.15.0-1109.111
linux-gcp-fips (Ubuntu package) - addressed in versions 5.15.0-1118.128+fips1, 6.8.0-1071.79+fips1
linux-aws-fips (Ubuntu package) - addressed in versions 5.15.0-1117.124+fips1, 6.8.0-1067.70+fips1
linux-azure-fips (Ubuntu package) - addressed in versions 5.15.0-1123.132+fips1, 6.8.0-1071.79+fips1
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-38.38~24.04.4
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1013.13~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1014.14~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1015.15
linux (Debian package) - update to 6.12.101-1
linux-azure-7.0 (Ubuntu package) - addressed in versions 7.0.0-1016.16~24.04.1, 7.0.0-1017.17~24.04.1

External References

Related Security Bulletins