CVE-2023-4515
This vulnerability affects the Linux kernel's SMB daemon (ksmbd). An attacker could send a specially crafted SMB request that bypasses size checks, potentially causing a denial of service or other impact. The issue has been fixed in a kernel patch that validates command request sizes.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Linux kernel 6.4, 6.5, and other versions that do not include the ksmbd request size validation patch. Typical users are system administrators running Linux servers that use SMB services.
Real-world impact
An attacker could send malformed SMB requests to cause a crash or denial of service, potentially disrupting services that rely on SMB.
Why this severity
The CVSS score of 9.1 reflects that the vulnerability can be exploited remotely without authentication, with no user interaction, and can lead to complete loss of availability (high impact).
What to do about it
- 01Update your Linux kernel to a version that includes the ksmbd request size validation patch (commit 2b9b8f3b68ed).
- 02Reboot the system to load the updated kernel.
NVD-referenced vendor advisory
Timeline
- Aug 16, 2025 · Aug 16, 2025PublishedDisclosed and added to the National Vulnerability Database.
- Aug 4, 2026 · 1d agoAdvisory updatedThe NVD record was last revised.
- Aug 4, 2026 · 1d agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.