CVE-2011-4040: NJStar Communicator MiniSmtp buffer overflow allows remote code execution

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 19 September 2026. Confidence: medium.

critical priorityThe flaw is remotely exploitable without authentication and yields full code execution (CVSS 10.0), and EPSS places it in the 99.2nd percentile for exploitation likelihood.

What it is

MiniSmtp 3.0.11818, shipped with NJStar Communicator, contains a buffer overflow (CWE-119) reachable through a crafted network packet. Because the flaw is remotely triggerable without credentials, it exposes any host running the affected MiniSmtp service to full compromise. The record is old and thin: no patch information, affected-version range beyond the stated build, or vendor advisory is provided.

Impact

An attacker can execute arbitrary code on the vulnerable system, gaining complete control of confidentiality, integrity and availability as reflected in the CVSS 2.0 score of 10.0.

Attack surface

The vector AV:N/AC:L/Au:N/C:C/I:C/A:C indicates the flaw is reached over the network with no authentication and no user interaction, by sending a malformed packet to the MiniSmtp service.

Exploitation

The CVE is not listed in CISA KEV and no ransomware use is documented; EPSS gives a 30-day exploitation probability of 0.65262 (99.2nd percentile), and the only references are US Government resource pages with no exploit tag.

What to do

• Apply the vendor patch or upgrade NJStar Communicator/MiniSmtp to a fixed build if one is available; the record does not name a fixed version, so confirm with NJStar.
• If no patch exists, stop or disable the MiniSmtp service and block its listening port at the host and network perimeter.
• Restrict network access to the MiniSmtp port to trusted hosts only, using firewall rules or segmentation.
• Replace the bundled MiniSmtp component with a maintained SMTP service if the product is still required.
• Monitor vendor and CERT/CC advisories for an updated fix, since the supplied references are only US Government resource pages.

Detection

• Inspect network traffic to the MiniSmtp port for oversized or malformed packets that could trigger the overflow.
• Monitor for unexpected process crashes or restarts of MiniSmtp/NJStar Communicator processes.
• Watch for anomalous child processes or outbound connections originating from the MiniSmtp service host.
• Audit hosts for the presence of NJStar Communicator with MiniSmtp 3.0.11818 and flag them for remediation.

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