Overview

In a compelling example of AI-assisted vulnerability research, a security researcher has used OpenAI’s o3 model to discover a use-after-free vulnerability in the Linux kernel’s SMB server component (ksmbd). Tracked as CVE-2025-37899, this vulnerability carries a CVSS score of 5.5, placing it in the Medium severity category.

While not classified as “critical,” the flaw is remotely exploitable without authentication, making it relevant for organizations that expose ksmbd to untrusted networks.

What Is CVE-2025-37899?

• Vulnerability: Use-after-free in the SMB logoff command handler
• CVSS Score: 5.5 (Medium)
• Attack Vector: Network
• Authentication Required: None
• Privileges Required: None
• Impact: Low confidentiality, integrity, and availability impact
• Scope: Unchanged

AI Discovery

Security researcher Sean Heelan leveraged OpenAI’s o3 model to analyze the ksmbd codebase and identify unsafe memory handling patterns that ultimately led to this vulnerability’s discovery.

Affected Systems

Only systems using the ksmbd kernel module are affected. This module is:

• Not enabled by default on most distributions.
• Primarily used in experimental or high-performance configurations.

Samba users and systems not running ksmbd are not affected.

Mitigation Guidance

🛠 Short-Term Recommendations

Disable ksmbd if not required:

sudo systemctl stop ksmbd sudo systemctl disable ksmbd

Restrict access to SMB (TCP 445) via firewalls.

🧩 Long-Term Recommendations

• Monitor for kernel updates and apply patches as they become available.
• Track vendor advisories:
  • Red Hat CVE Tracker
  • Ubuntu CVE Tracker

Detection and Indicators of Compromise

While exploitation is not confirmed in the wild, defenders should monitor for unusual ksmbd behavior.

Indicators of Interest

SIEM Detection Queries

Splunk

index=syslog OR index=os_logs sourcetype=kernel_logs
"ksmbd" AND ("logoff" OR "use-after-free")

Azure Sentinel

Syslog | where ProcessName contains "ksmbd" and (Message contains "logoff" or Message contains "use-after-free")

Elastic KQL

process.name : "ksmbd" and (message : "*logoff*" or message : "*use-after-free*")

Wazuh

rule.groups: "kernel" and data: "ksmbd" and (data: "logoff" or data: "use-after-free")

Final Thoughts

Although CVE-2025-37899 is not critical, its remote attack vector, unauthenticated nature, and discovery via AI make it notable. This event also showcases how artificial intelligence can assist defenders in proactively uncovering vulnerabilities before they’re exploited. If you’d like help identifying exposure or patching your systems, please contact us to learn more about our services.

🔐 Secure Today. Defend Tomorrow.