Vulnerability Database

327,594

Total vulnerabilities in the database

CVE-2021-37706

PJSIP is a free and open source multimedia communication library written in C language implementing standard based protocols such as SIP, SDP, RTP, STUN, TURN, and ICE. In affected versions if the incoming STUN message contains an ERROR-CODE attribute, the header length is not checked before performing a subtraction operation, potentially resulting in an integer underflow scenario. This issue affects all users that use STUN. A malicious actor located within the victim’s network may forge and send a specially crafted UDP (STUN) message that could remotely execute arbitrary code on the victim’s machine. Users are advised to upgrade as soon as possible. There are no known workarounds.

  • Published: Dec 22, 2021
  • Updated: Nov 5, 2025
  • CVE: CVE-2021-37706
  • Severity: High
  • Exploit:

CVSS v3:

  • Severity: High
  • Score: 7.3
  • AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS v2:

  • Severity: High
  • Score: 9.3
  • AV:N/AC:M/Au:N/C:C/I:C/A:C

CWEs:

Software From Fixed in
teluu / pjsip - 2.11.1.x
asterisk / certified_asterisk 16.8.0-cert12 16.8.0-cert12.x
asterisk / certified_asterisk 16.8.0-cert11 16.8.0-cert11.x
asterisk / certified_asterisk 16.8.0-cert10 16.8.0-cert10.x
asterisk / certified_asterisk 16.8.0-cert9 16.8.0-cert9.x
asterisk / certified_asterisk 16.8.0-cert8 16.8.0-cert8.x
asterisk / certified_asterisk 16.8.0-cert7 16.8.0-cert7.x
asterisk / certified_asterisk 16.8.0-cert6 16.8.0-cert6.x
asterisk / certified_asterisk 16.8.0-cert5 16.8.0-cert5.x
asterisk / certified_asterisk 16.8.0-cert4 16.8.0-cert4.x
asterisk / certified_asterisk 16.8.0-cert3 16.8.0-cert3.x
asterisk / certified_asterisk 16.8.0-cert2 16.8.0-cert2.x
asterisk / certified_asterisk 16.8.0-cert1 16.8.0-cert1.x
asterisk / certified_asterisk - 16.8.0
asterisk / certified_asterisk 16.8.0 16.8.0.x
sangoma / asterisk 16.0.0 16.24.1
sangoma / asterisk 19.0.0 19.2.1
sangoma / asterisk 18.0.0 18.10.1
debian / debian_linux 9.0 9.0.x
debian / debian_linux 10.0 10.0.x

Frequently Asked Questions

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.