CVE-2026-89633
A critical vulnerability in the Linux kernel’s SMB client allows attackers to read or write memory outside the intended buffer by sending a specially crafted DataOffset value. The flaw occurs because the kernel does not validate the DataOffset before copying data, which can overwrite kernel memory or read sensitive data. This could let an attacker gain full control of the affected system.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Linux kernel SMB client in any kernel version before the fix; affects all Linux systems that use the SMB client.
Real-world impact
An attacker could read or write arbitrary kernel memory, potentially taking full control of the system.
Why this severity
The CVSS score of 9.8 reflects that the vulnerability is exploitable over the network with no authentication or user interaction, and it allows complete compromise of confidentiality, integrity, and availability. The lack of validation on the DataOffset field gives attackers unrestricted access to kernel memory.
What to do about it
- 01Upgrade the Linux kernel to a version that includes the bounds‑checking patch for SMB client DataOffset handling.
- 02Reboot the system to load the updated kernel.
NVD description indicates the vulnerability has been resolved.
Timeline
- Sep 11, 2026 · 2d agoPublishedDisclosed and added to the National Vulnerability Database.
- Sep 13, 2026 · 7h agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.