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5.3

Asterisk Open Source and Certified Asterisk - SIP Crash on Certain Calls

CVE-2020-28327 · published 5 years ago
Summary

A bug was found in Asterisk Open Source and Certified Asterisk that can cause the software to crash when handling certain SIP calls over a secure connection. This issue only affects calls made over TCP or TLS, and requires the client to be authenticated or anonymous calling to be enabled. To fix this issue, update to the latest version of Asterisk Open Source or Certified Asterisk.

What to do

The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.

Affected software
VendorProductAffected versions
digium certified_asterisk 16.8
cpe:2.3:a:digium:certified_asterisk:16.8:-:*:*:*:*:*:*
sangoma asterisk >= 13.0.0, < 13.37.1
>= 16.0.0, < 16.14.1
>= 17.0.0, < 17.8.1
>= 18.0.0, < 18.0.1
cpe:2.3:a:sangoma:asterisk:*:*:*:*:*:*:*:*
Original advisory text
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...
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.
References
Fix within
Internet-facing 60 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit (estimated)
  • Gives an attacker partial control (estimated)
Severity
5.3 Medium
Exploitation
2% chance of attack within 30 days
Type
CWE-404Improper Resource Shutdown or Release
Timeline
Published6 Nov 2020
Updated3 Nov 2026
First seen9 Jul 2026
Sources
CVE-2020-28327 · OSV
CVE-2020-28327 · NVD
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