An issue was discovered in Asterisk Open Source 11.x before 11.25.1, 13.x before 13.13.1, and 14.x before 14.2.1 and Certified Asterisk 11.x before 11.6-cert16 and 13.x before 13.8-cert4. The chan_sip channel driver has a liberal definition for whitespace when attempting to strip the content between a SIP header name and a colon character. Rather than following RFC 3261 and stripping only spaces and horizontal tabs, Asterisk treats any non-printable ASCII character as if it were whitespace. This means that headers such as Contact\x01: will be seen as a valid Contact header. This mostly does not pose a problem until Asterisk is placed in tandem with an authenticating SIP proxy. In such a case, a crafty combination of valid and invalid To headers can cause a proxy to allow an INVITE request into Asterisk without authentication since it believes the request is an in-dialog request. However, because of the bug described above, the request will look like an out-of-dialog request to Asterisk. Asterisk will then process the request as a new call. The result is that Asterisk can process calls from unvetted sources without any authentication. If you do not use a proxy for authentication, then this issue does not affect you. If your proxy is dialog-aware (meaning that the proxy keeps track of what dialogs are currently valid), then this issue does not affect you. If you use chan_pjsip instead of chan_sip, then this issue does not affect you.
| Software | From | Fixed in |
|---|---|---|
| digium / asterisk | 13.1.0 | 13.1.0.x |
| digium / asterisk | 13.2.1 | 13.2.1.x |
| digium / asterisk | 13.8.0-rc1 | 13.8.0-rc1.x |
| digium / asterisk | 11.14.0 | 11.14.0.x |
| digium / asterisk | 13.7.1 | 13.7.1.x |
| digium / asterisk | 11.2.0-rc2 | 11.2.0-rc2.x |
| digium / asterisk | 11.21.0 | 11.21.0.x |
| digium / asterisk | 11.22.0 | 11.22.0.x |
| digium / asterisk | 11.10.2 | 11.10.2.x |
| digium / asterisk | 11.0.0-rc2 | 11.0.0-rc2.x |
| digium / asterisk | 11.2.0 | 11.2.0.x |
| digium / asterisk | 11.1.1 | 11.1.1.x |
| digium / asterisk | 13.1.1 | 13.1.1.x |
| digium / asterisk | 11.21.1 | 11.21.1.x |
| digium / asterisk | 13.4.0 | 13.4.0.x |
| digium / asterisk | 11.10.1 | 11.10.1.x |
| digium / asterisk | 11.16.0 | 11.16.0.x |
| digium / asterisk | 11.11.0 | 11.11.0.x |
| digium / asterisk | 11.12.1 | 11.12.1.x |
| digium / asterisk | 14.0.0-beta1 | 14.0.0-beta1.x |
| digium / asterisk | 11.23.0-rc1 | 11.23.0-rc1.x |
| digium / asterisk | 13.2.0 | 13.2.0.x |
| digium / asterisk | 11.0.2 | 11.0.2.x |
| digium / asterisk | 11.2.0-rc1 | 11.2.0-rc1.x |
| digium / asterisk | 11.0.0-beta1 | 11.0.0-beta1.x |
| digium / asterisk | 11.18.0 | 11.18.0.x |
| digium / asterisk | 11.17.0 | 11.17.0.x |
| digium / asterisk | 13.3.2 | 13.3.2.x |
| digium / asterisk | 13.0.1 | 13.0.1.x |
| digium / asterisk | 11.7.0 | 11.7.0.x |
| digium / asterisk | 11.22.0-rc1 | 11.22.0-rc1.x |
| digium / asterisk | 13.7.0 | 13.7.0.x |
| digium / asterisk | 14.1.1 | 14.1.1.x |
| digium / asterisk | 11.23.1 | 11.23.1.x |
| digium / asterisk | 11.12.0 | 11.12.0.x |
| digium / asterisk | 13.10.0-rc1 | 13.10.0-rc1.x |
| digium / asterisk | 13.10.0 | 13.10.0.x |
| digium / asterisk | 11.15.1 | 11.15.1.x |
| digium / asterisk | 11.0.0 | 11.0.0.x |
| digium / asterisk | 11.10.0 | 11.10.0.x |
| digium / asterisk | 13.8.0 | 13.8.0.x |
| digium / asterisk | 13.11.1 | 13.11.1.x |
| digium / asterisk | 11.25.0 | 11.25.0.x |
| digium / asterisk | 11.4.0 | 11.4.0.x |
| digium / asterisk | 13.11.0 | 13.11.0.x |
| digium / asterisk | 11.13.0 | 11.13.0.x |
| digium / asterisk | 13.9.0 | 13.9.0.x |
| digium / asterisk | 13.12.0 | 13.12.0.x |
| digium / asterisk | 13.3.0 | 13.3.0.x |
| digium / asterisk | 11.24.1 | 11.24.1.x |
| digium / asterisk | 14.0.0-rc1 | 14.0.0-rc1.x |
| digium / asterisk | 13.8.1 | 13.8.1.x |
| digium / asterisk | 13.12.2 | 13.12.2.x |
| digium / asterisk | 11.1.0-rc3 | 11.1.0-rc3.x |
| digium / asterisk | 13.0.0-beta1 | 13.0.0-beta1.x |
| digium / asterisk | 11.8.1 | 11.8.1.x |
| digium / asterisk | 14.2.0 | 14.2.0.x |
| digium / asterisk | 14.0.0 | 14.0.0.x |
| digium / asterisk | 14.1.2 | 14.1.2.x |
| digium / asterisk | 11.19.0 | 11.19.0.x |
| digium / asterisk | 11.1.2 | 11.1.2.x |
| digium / asterisk | 13.0.0 | 13.0.0.x |
| digium / asterisk | 13.13.0 | 13.13.0.x |
| digium / asterisk | 11.21.2 | 11.21.2.x |
| digium / asterisk | 11.14.2 | 11.14.2.x |
| digium / asterisk | 13.9.1 | 13.9.1.x |
| digium / asterisk | 14.0.2 | 14.0.2.x |
| digium / asterisk | 11.5.0 | 11.5.0.x |
| digium / asterisk | 11.15.0 | 11.15.0.x |
| digium / asterisk | 13.3.1 | 13.3.1.x |
| digium / asterisk | 11.2.2 | 11.2.2.x |
| digium / asterisk | 14.0.0-rc2 | 14.0.0-rc2.x |
| digium / asterisk | 11.14.1 | 11.14.1.x |
| digium / asterisk | 13.0.2 | 13.0.2.x |
| digium / asterisk | 11.1.0 | 11.1.0.x |
| digium / asterisk | 13.7.2 | 13.7.2.x |
| digium / asterisk | 11.17.1 | 11.17.1.x |
| digium / asterisk | 11.0.0-beta2 | 11.0.0-beta2.x |
| digium / asterisk | 11.1.0-rc1 | 11.1.0-rc1.x |
| digium / asterisk | 13.11.2 | 13.11.2.x |
| digium / asterisk | 14.0.0-beta2 | 14.0.0-beta2.x |
| digium / asterisk | 14.0.1 | 14.0.1.x |
| digium / asterisk | 11.0.1 | 11.0.1.x |
| digium / asterisk | 11.8.0 | 11.8.0.x |
| digium / asterisk | 13.12.1 | 13.12.1.x |
| digium / asterisk | 11.6.0 | 11.6.0.x |
| digium / asterisk | 13.5.0 | 13.5.0.x |
| digium / asterisk | 11.23.0 | 11.23.0.x |
| digium / asterisk | 13.8.2 | 13.8.2.x |
| digium / asterisk | 13.0.0-beta3 | 13.0.0-beta3.x |
| digium / asterisk | 13.6.0 | 13.6.0.x |
| digium / asterisk | 14.1.0 | 14.1.0.x |
| digium / asterisk | 11.24.0 | 11.24.0.x |
| digium / asterisk | 11.9.0 | 11.9.0.x |
| digium / asterisk | 11.2.1 | 11.2.1.x |
| digium / asterisk | 11.5.1 | 11.5.1.x |
| digium / asterisk | 11.3.0 | 11.3.0.x |
| digium / asterisk | 11.13.1 | 11.13.1.x |
| digium / asterisk | 11.20.0 | 11.20.0.x |
| digium / asterisk | 13.0.0-beta2 | 13.0.0-beta2.x |
| digium / asterisk | 11.6.1 | 11.6.1.x |
| digium / asterisk | 11.0.0-rc1 | 11.0.0-rc1.x |
| digium / certified_asterisk | 11.6-cert13 | 11.6-cert13.x |
| digium / certified_asterisk | 11.4.0-rc3 | 11.4.0-rc3.x |
| digium / certified_asterisk | 11.6-cert8 | 11.6-cert8.x |
| digium / certified_asterisk | 11.6-cert2 | 11.6-cert2.x |
| digium / certified_asterisk | 11.1.0-rc3 | 11.1.0-rc3.x |
| digium / certified_asterisk | 11.6-cert7 | 11.6-cert7.x |
| digium / certified_asterisk | 11.6-cert4 | 11.6-cert4.x |
| digium / certified_asterisk | 11.3.0-rc2 | 11.3.0-rc2.x |
| digium / certified_asterisk | 11.6-cert3 | 11.6-cert3.x |
| digium / certified_asterisk | 11.2.0-rc1 | 11.2.0-rc1.x |
| digium / certified_asterisk | 11.3.0 | 11.3.0.x |
| digium / certified_asterisk | 11.0.0 | 11.0.0.x |
| digium / certified_asterisk | 11.6-cert9 | 11.6-cert9.x |
| digium / certified_asterisk | 11.0.0-rc1 | 11.0.0-rc1.x |
| digium / certified_asterisk | 11.5.0-rc2 | 11.5.0-rc2.x |
| digium / certified_asterisk | 11.6-cert12 | 11.6-cert12.x |
| digium / certified_asterisk | 11.6-cert1 | 11.6-cert1.x |
| digium / certified_asterisk | 11.4.0 | 11.4.0.x |
| digium / certified_asterisk | 11.4.0-rc1 | 11.4.0-rc1.x |
| digium / certified_asterisk | 11.6.0 | 11.6.0.x |
| digium / certified_asterisk | 11.6-cert1_rc2 | 11.6-cert1_rc2.x |
| digium / certified_asterisk | 11.3.0-rc1 | 11.3.0-rc1.x |
| digium / certified_asterisk | 11.2.0-rc2 | 11.2.0-rc2.x |
| digium / certified_asterisk | 11.1.0-rc2 | 11.1.0-rc2.x |
| digium / certified_asterisk | 11.6-cert14 | 11.6-cert14.x |
| digium / certified_asterisk | 11.6-cert15 | 11.6-cert15.x |
| digium / certified_asterisk | 11.6.0-rc1 | 11.6.0-rc1.x |
| digium / certified_asterisk | 11.4.0-rc2 | 11.4.0-rc2.x |
| digium / certified_asterisk | 11.0.0-rc2 | 11.0.0-rc2.x |
| digium / certified_asterisk | 11.5.0-rc1 | 11.5.0-rc1.x |
| digium / certified_asterisk | 11.6-cert1_rc1 | 11.6-cert1_rc1.x |
| digium / certified_asterisk | 11.6-cert11 | 11.6-cert11.x |
| digium / certified_asterisk | 11.2.0 | 11.2.0.x |
| digium / certified_asterisk | 11.6-cert6 | 11.6-cert6.x |
| digium / certified_asterisk | 11.6-cert10 | 11.6-cert10.x |
| digium / certified_asterisk | 11.5.0 | 11.5.0.x |
| digium / certified_asterisk | 11.1.0-rc1 | 11.1.0-rc1.x |
| digium / certified_asterisk | 11.1.0 | 11.1.0.x |
| digium / certified_asterisk | 11.6-cert5 | 11.6-cert5.x |
| digium / certified_asterisk | 11.6.0-rc2 | 11.6.0-rc2.x |
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.