Use-after-free in Linux kernel - CVE-2026-64397

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Main Vulnerability Database Vulnerabilities #VU139567

Use-after-free in Linux kernel - CVE-2026-64397

Published: July 27, 2026


Vulnerability identifier: #VU139567
CSH Severity: Medium
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64397
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote user to cause a denial of service.

The vulnerability exists due to a use-after-free in smb2_query_dir() and the ksmbd directory enumeration state when handling concurrent QUERY_DIRECTORY requests using the same file handle. A remote user can send concurrent QUERY_DIRECTORY requests on the same file handle to cause a denial of service.

The issue occurs because a pointer to stack-allocated private data is stored in shared readdir state and can be overwritten while an iterate_dir() callback is still using it.


Affected software

Linux kernel
openEuler
Ubuntu
linux (Ubuntu package)
linux-lowlatency (Ubuntu package)
linux-gcp (Ubuntu package)
linux-azure (Ubuntu package)
linux-aws (Ubuntu package)
linux-ibm (Ubuntu package)
linux-oracle (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux-realtime (Ubuntu package)
linux-fips (Ubuntu package)
linux-gkeop (Ubuntu package)
linux-gke (Ubuntu package)
linux-azure-fips (Ubuntu package)
linux-aws-fips (Ubuntu package)
linux-gcp-fips (Ubuntu package)
bpftool
kernel
python3-perf-debuginfo
python3-perf
perf-debuginfo
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel-source
kernel-headers
kernel-devel
kernel-debugsource
kernel-debuginfo
bpftool-debuginfo
kernel-tools
linux-nvidia-tegra (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-azure-7.0 (Ubuntu package)
linux-nvidia-7.0 (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-raspi (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

How to mitigate CVE-2026-64397

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 6.8.0-147.147, 7.0.0-31.31~24.04.1, 7.0.0-31.31, 7.0.0-31.31.1, 7.0.0-1006.7, 7.0.0-1011.11~24.04.1, 7.0.0-1012.12~24.04.1, 7.0.0-1012.12
linux-lowlatency (Ubuntu package) - update to 6.8.0-147.147.1
linux-gcp (Ubuntu package) - update to 6.8.0-1071.79
linux-azure (Ubuntu package) - addressed in versions 6.8.0-1071.79, 7.0.0-1011.11, 7.0.0-1014.14
linux-aws (Ubuntu package) - update to 6.8.0-1067.70
linux-ibm (Ubuntu package) - addressed in versions 6.8.0-1067.68, 7.0.0-1013.13
linux-oracle (Ubuntu package) - update to 6.8.0-1064.67
linux-azure-fde (Ubuntu package) - update to 6.8.0-1069.76
linux-realtime (Ubuntu package) - update to 6.8.1-1062.63
linux-fips (Ubuntu package) - update to 6.8.0-147.147+fips1
linux-gkeop (Ubuntu package) - update to 6.8.0-1052.56
linux-gke (Ubuntu package) - update to 6.8.0-1066.74
linux-azure-fips (Ubuntu package) - update to 6.8.0-1071.79+fips1
linux-aws-fips (Ubuntu package) - update to 6.8.0-1067.70+fips1
linux-gcp-fips (Ubuntu package) - update to 6.8.0-1071.79+fips1
bpftool - update to 5.10.0-327.0.0.228
kernel - update to 5.10.0-327.0.0.228
python3-perf-debuginfo - update to 5.10.0-327.0.0.228
python3-perf - update to 5.10.0-327.0.0.228
perf-debuginfo - update to 5.10.0-327.0.0.228
perf - update to 5.10.0-327.0.0.228
kernel-tools-devel - update to 5.10.0-327.0.0.228
kernel-tools-debuginfo - update to 5.10.0-327.0.0.228
kernel-source - update to 5.10.0-327.0.0.228
kernel-headers - update to 5.10.0-327.0.0.228
kernel-devel - update to 5.10.0-327.0.0.228
kernel-debugsource - update to 5.10.0-327.0.0.228
kernel-debuginfo - update to 5.10.0-327.0.0.228
bpftool-debuginfo - update to 5.10.0-327.0.0.228
kernel-tools - update to 5.10.0-327.0.0.228
linux-nvidia-tegra (Ubuntu package) - update to 6.8.0-1035.38
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13
linux-azure-7.0 (Ubuntu package) - update to 7.0.0-1014.14~24.04.1
linux-nvidia-7.0 (Ubuntu package) - update to 7.0.0-1018.18~24.04.1
linux-nvidia (Ubuntu package) - update to 7.0.0-1018.18
linux-raspi (Ubuntu package) - update to 7.0.0-1019.19
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2018.18

External References

Related Security Bulletins