CVE-2008-4834: Windows SMB Server Service buffer overflow allows remote code execution

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 20 September 2026. Confidence: high.

critical priorityCVSS 2.0 base score of 10 with network-reachable, unauthenticated remote code execution and a very high EPSS percentile make this a top remediation priority despite no KEV listing.

What it is

A buffer overflow exists in the SMB implementation of the Windows Server service, triggered by malformed field values inside SMB packets in an NT Trans request. Because SMB is reachable over the network without authentication, a remote attacker can corrupt memory and potentially run arbitrary code with system privileges.

Impact

Successful exploitation gives the attacker remote code execution in the context of the Server service, typically SYSTEM, allowing full compromise of the host. No user interaction or credentials are required.

Attack surface

Reached over the network via SMB (TCP 445/139) by sending a crafted NT Trans request; the CVSS vector AV:N/AC:L/Au:N confirms no authentication and no user interaction are needed.

Exploitation

Not listed in CISA KEV and no ransomware associations are documented, but EPSS is 0.45756 (98.7th percentile), indicating a high modeled likelihood of exploitation activity; references include vendor and US-CERT advisories but no public exploit tag.

What to do

• Apply Microsoft security bulletin MS09-001 immediately on all affected Windows 2000 SP4, XP SP2/SP3, and Server 2003 SP1/SP2 systems.
• Block inbound SMB (TCP 445 and 139) at network boundaries and between untrusted network segments.
• Disable the Server service or SMB where it is not required on exposed hosts.
• Restrict SMB access to trusted management networks and enforce host firewall rules.
• Retire or isolate unsupported Windows 2000 and XP systems that cannot be patched.

Detection

• Monitor SMB traffic for malformed or oversized NT Trans requests, especially unusual field values in SMB headers.
• Alert on Server service crashes or unexpected restarts (event log entries for service failures) on SMB-exposed hosts.
• Baseline and review inbound SMB connections from unexpected external or cross-segment sources.
• Use IDS/IPS signatures for MS09-001 SMB buffer overflow attempts where available.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.