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CVE-2021-26717

HIGH
7.5
CVSS Score
Published: February 18, 2021 at 07:39 PM UTC
Updated: June 17, 2026 at 03:43 AM UTC
2 products affected across 1 vendorAsteriskCertified Asterisk

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Severity
HIGH7.5
Exploit prediction
EPSS 2%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Asterisk· Digium
95%
16.0.0 ≤ v < 16.16.117.0.0 ≤ v < 17.9.218.0 ≤ v < 18.2.1
Affected range stops below 16.16.1, so it looks safe — our inference, not a vendor statement
Affected range stops below 17.9.2, so it looks safe — our inference, not a vendor statement
Affected range stops below 18.2.1, so it looks safe — our inference, not a vendor statement
Certified Asterisk· Digium
95%
16.816.8 cert1-rc116.8 cert1-rc216.8 cert1-rc316.8 cert1-rc416.8 cert216.8 cert316.8 cert416.8 cert4-rc116.8 cert4-rc216.8 cert4-rc316.8 cert4-rc416.8 cert5

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (5)

x_refsource_MISCThird Party Advisory
Source: [email protected]
http://packetstormsecurity.com/files/161471/Asterisk-Project-Security-Advisory-AST-2021-002.html
Mailing Listx_refsource_FULLDISCPatchThird Party Advisory
Source: [email protected]
http://seclists.org/fulldisclosure/2021/Feb/58
x_refsource_MISCVendor Advisory
Source: [email protected]
https://downloads.asterisk.org/pub/security/
x_refsource_CONFIRMVendor Advisory
Source: [email protected]
https://downloads.asterisk.org/pub/security/AST-2021-002.html
x_refsource_CONFIRMIssue TrackingPatchVendor Advisory
Source: [email protected]
https://issues.asterisk.org/jira/browse/ASTERISK-29203

CVSS

7.5HIGH[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
NVD-CWE-noinfo

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