Vulnerability record · CVE-2006-3524 · published 12 July 2006
CVE-2006-3524: sipXtapi SIP stack buffer overflow via long CSeq in INVITE
Sipfoundry · Sipxtapi
SIPfoundry sipXtapi releases before 20060324 contain a buffer overflow triggered by an overly long CSeq header value in a SIP INVITE message. Because the flaw is reachable over the network without authentication, a remote party that can send SIP traffic to the affected stack can corrupt memory and potentially execute code.
Description
Buffer overflow in SIPfoundry sipXtapi released before 20060324 allows remote attackers to execute arbitrary code via a long CSeq field value in an INVITE message.
AV:N/AC:L/Au:N/C:P/I:P/A:P
Automated analysis
high priorityRemote, unauthenticated code execution with public exploit references and very high EPSS, though the product is a dated 2006 SIP stack and not in KEV.
What it is
SIPfoundry sipXtapi releases before 20060324 contain a buffer overflow triggered by an overly long CSeq header value in a SIP INVITE message. Because the flaw is reachable over the network without authentication, a remote party that can send SIP traffic to the affected stack can corrupt memory and potentially execute code.
Impact
An attacker gains the ability to execute arbitrary code in the context of the process running sipXtapi, or at minimum crash it, by sending a crafted INVITE. This can compromise the SIP endpoint or service handling the call.
Attack surface
Reached over the network by sending a SIP INVITE with a long CSeq field to a service using sipXtapi; the CVSS vector (AV:N/AC:L/Au:N) indicates no authentication and no user interaction are required.
Exploitation
No CISA KEV listing, but EPSS is very high (0.675, ~99th percentile) and a SecurityFocus reference is tagged Exploit, indicating public exploit material exists.
What to do
- Upgrade sipXtapi to a build released on or after 20060324, which is the version boundary given in the advisory.
- If upgrade is not immediately possible, restrict SIP traffic to trusted peers and block unsolicited INVITEs at the network edge.
- Enforce strict SIP header length limits and validate CSeq values in any front-end proxy or SBC before they reach sipXtapi.
- Run the SIP service with least privilege and isolate it from sensitive hosts to limit the impact of code execution.
Detection
- Inspect SIP INVITE messages for abnormally long CSeq header values and alert on those exceeding expected lengths.
- Monitor the sipXtapi process for crashes or unexpected restarts correlated with inbound SIP traffic.
- Watch for unusual outbound connections or child processes spawned by the SIP service, which may indicate successful exploitation.
This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.
Affected products
1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.
References
Track CVE-2006-3524 inside VULONE
Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.
Source: NIST National Vulnerability Database (record CVE-2006-3524), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.
