Vulnerability Database

327,594

Total vulnerabilities in the database

CVE-2020-28327

A res_pjsip_session crash was discovered in Asterisk Open Source 13.x before 13.37.1, 16.x before 16.14.1, 17.x before 17.8.1, and 18.x before 18.0.1. and Certified Asterisk before 16.8-cert5. Upon receiving a new SIP Invite, Asterisk did not return the created dialog locked or referenced. This caused a gap between the creation of the dialog object, and its next use by the thread that created it. Depending on some off-nominal circumstances and timing, it was possible for another thread to free said dialog in this gap. Asterisk could then crash when the dialog object, or any of its dependent objects, were dereferenced or accessed next by the initial-creation thread. Note, however, that this crash can only occur when using a connection-oriented protocol (e.g., TCP or TLS, but not UDP) for SIP transport. Also, the remote client must be authenticated, or Asterisk must be configured for anonymous calling.

  • Published: Nov 6, 2020
  • Updated: Nov 16, 2025
  • CVE: CVE-2020-28327
  • Severity: Medium
  • Exploit:

CVSS v3:

  • Severity: Medium
  • Score: 5.3
  • AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS v2:

  • Severity: Low
  • Score: 2.1
  • AV:N/AC:H/Au:S/C:N/I:N/A:P

CWEs:

Software From Fixed in
digium / certified_asterisk 16.8-cert1-rc1 16.8-cert1-rc1.x
digium / certified_asterisk 16.8-cert1-rc2 16.8-cert1-rc2.x
digium / certified_asterisk 16.8-cert1-rc3 16.8-cert1-rc3.x
digium / certified_asterisk 16.8-cert1-rc4 16.8-cert1-rc4.x
digium / certified_asterisk 16.8-cert2 16.8-cert2.x
digium / certified_asterisk 16.8-cert3 16.8-cert3.x
digium / certified_asterisk 16.8-cert4 16.8-cert4.x
digium / certified_asterisk 16.8-cert4-rc1 16.8-cert4-rc1.x
digium / certified_asterisk 16.8-cert4-rc2 16.8-cert4-rc2.x
digium / certified_asterisk 16.8-cert4-rc3 16.8-cert4-rc3.x
digium / certified_asterisk 16.8-cert4-rc4 16.8-cert4-rc4.x
digium / certified_asterisk 16.8 16.8.x
sangoma / asterisk 16.0.0 16.14.1
sangoma / asterisk 13.0.0 13.37.1
sangoma / asterisk 18.0.0 18.0.1
sangoma / asterisk 17.0.0 17.8.1

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.