CVE-2021-26717
When re-negotiating for T.38, if the initial remote response was delayed just enough, Asterisk would send both audio and T.38 in the SDP.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.20%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
An issue was discovered in Sangoma Asterisk 16.x before 16.16.1, 17.x before 17.9.2, and 18.x before 18.2.1 and Certified Asterisk before 16.8-cert6. When re-negotiating for T.38, if the initial remote response was delayed just enough, Asterisk would send both audio and T.38 in the SDP. If this happened, and the remote responded with a declined T.38 stream, then Asterisk would crash.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 2.20% probability · 82th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Affected
- digium/asterisk · digium/certified asterisk
- Source
- cve@mitre.org
EPSS 2.2% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://packetstormsecurity.com/files/161471/Asterisk-Project-Security-Advisory-AST-2021-002.htmlThird Party Advisory
- http://seclists.org/fulldisclosure/2021/Feb/58Mailing List, Patch, Third Party Advisory
- https://downloads.asterisk.org/pub/security/Vendor Advisory
- https://downloads.asterisk.org/pub/security/AST-2021-002.htmlVendor Advisory
- https://issues.asterisk.org/jira/browse/ASTERISK-29203Issue Tracking, Patch, Vendor Advisory
- http://packetstormsecurity.com/files/161471/Asterisk-Project-Security-Advisory-AST-2021-002.htmlThird Party Advisory
- http://seclists.org/fulldisclosure/2021/Feb/58Mailing List, Patch, Third Party Advisory
- https://downloads.asterisk.org/pub/security/Vendor Advisory
- https://downloads.asterisk.org/pub/security/AST-2021-002.htmlVendor Advisory
- https://issues.asterisk.org/jira/browse/ASTERISK-29203Issue Tracking, Patch, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.