CVE-2026-64397
A critical flaw in the Linux kernel’s ksmbd SMB file server allows attackers to send multiple directory‑listing requests on the same file handle, causing a use‑after‑free that can lead to arbitrary code execution or denial of service. The vulnerability has been fixed by adding a per‑file mutex to serialize these requests. Updating the kernel removes the risk.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Linux kernel systems that include the ksmbd SMB file server component and are running a kernel version before the patch.
Real-world impact
An attacker could trigger a use‑after‑free, potentially executing arbitrary code or crashing the system, resulting in denial of service or privilege escalation.
Why this severity
The CVSS score of 9.8 reflects that the flaw is network‑exploitable with no authentication or user interaction, and it can compromise confidentiality, integrity, and availability.
What to do about it
- 01Upgrade the Linux kernel to a version that includes the fix.
NVD description indicates the vulnerability has been resolved.
Timeline
- Jul 25, 2026 · 7d agoPublishedDisclosed and added to the National Vulnerability Database.
- Jul 27, 2026 · 5d agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.