What is CVE-2020-35776?

CVE-2020-35776 is a medium-severity vulnerability in Digium Asterisk, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 6.5/10. Published 2021-02-18.

How severe is CVE-2020-35776?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Buffer overflow in Digium Asterisk

CVE-2020-35776

A buffer overflow in res_pjsip_diversion.c in Sangoma Asterisk versions 13.38.1, 16.15.1, 17.9.1, and 18.1.1 allows remote attacker to crash Asterisk by deliberately misusing SIP 181 responses.

Vulnerability class: Buffer Overflow

Published 2021-02-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.041 (90.3th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 90th percentile — 90.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.039 · newest: 0.041 · change: +0.001

Affected products

Digium Asterisk

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

References

issues.asterisk.org/ (Issue Tracking, Vendor Advisory)
seclists.org/fulldisclosure/2021/Feb/57 (mailing-list, Mailing List, Third Party Advisory)
downloads.asterisk.org/pub/security/AST-2021-001.html (Vendor Advisory)
issues.asterisk.org/jira/browse/ASTERISK-29227 (Exploit, Patch, Issue Tracking, Vendor Advisory)
packetstormsecurity.com/files/161470/Asterisk-Project-Security-Advisory-AST-202… (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2020-35776?: CVE-2020-35776 is a medium-severity vulnerability in Digium Asterisk, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 6.5/10. Published 2021-02-18.
How severe is CVE-2020-35776?: Medium severity. CVSS v3 base score is 6.5 out of 10.