What is CVE-2006-5551?

CVE-2006-5551 is a vulnerability in Qksoft Qk Smtp. Published 2006-10-26.

Is CVE-2006-5551 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Qksoft Qk Smtp

CVE-2006-5551

Stack-based buffer overflow in QK SMTP 3.01 and earlier might allow remote attackers to execute arbitrary code via a long argument to the RCPT TO command.

Published 2006-10-26 · last modified 2026-06-16.

CVSS v2 metric

CVSS v2 base score 7.5 (High). Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P. This CVE predates CVSS v3 and has no v3 score from NVD.

EPSS exploit prediction

EPSS: 0.052 (92.2th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 92nd percentile — 92.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.051 · newest: 0.052 · change: +0.001

Affected products

Qksoft Qk Smtp

Public proof-of-concept exploits

ARPSyndicate/cve-scores

References

securitytracker.com/id (Exploit, vdb-entry)
www.securityfocus.com/bid/20681 (Exploit, vdb-entry)
www.exploit-db.com/exploits/2625 (exploit)
secunia.com/advisories/22563 (Vendor Advisory, third-party-advisory)
www.vupen.com/english/advisories/2006/4169 (vdb-entry)

Frequently asked questions

What is CVE-2006-5551?: CVE-2006-5551 is a vulnerability in Qksoft Qk Smtp. Published 2006-10-26.
Is CVE-2006-5551 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.