What is CVE-2021-32558?

CVE-2021-32558 is a high-severity vulnerability in Digium Asterisk, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 7.5/10. Published 2021-07-30.

How severe is CVE-2021-32558?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2021-32558 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Digium Asterisk

CVE-2021-32558

An issue was discovered in Sangoma Asterisk 13.x before 13.38.3, 16.x before 16.19.1, 17.x before 17.9.4, and 18.x before 18.5.1, and Certified Asterisk before 16.8-cert10. If the IAX2 channel driver receives a packet that contains an unsupported media format, a crash can occur.

Published 2021-07-30 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.092 (95.2th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 95th percentile — 95.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.091 · newest: 0.092 · change: +0.001

Affected products

Digium Asterisk
Digium Certified Asterisk — versions 16.8
Debian Linux — versions 9.0, 11.0

Weakness classification (CWE)

CWE-74 — Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection)

Public proof-of-concept exploits

n0-traces/cve_

References

seclists.org/fulldisclosure/2021/Jul/49 (mailing-list, Patch, Mailing List, Third Party Advisory)
packetstormsecurity.com/files/163639/Asterisk-Project-Security-Advisory-AST-202… (Patch, VDB Entry, Third Party Advisory)
downloads.asterisk.org/pub/security/AST-2021-008.html (Patch, Vendor Advisory)
issues.asterisk.org/jira/browse/ASTERISK-29392 (Exploit, Patch, Issue Tracking, Vendor Advisory)
lists.debian.org/debian-lts-announce/2021/08/msg00005.html (mailing-list, Mailing List, Third Party Advisory)
www.debian.org/security/2021/dsa-4999 (vendor-advisory, Third Party Advisory)

Frequently asked questions

What is CVE-2021-32558?: CVE-2021-32558 is a high-severity vulnerability in Digium Asterisk, classified under Improper Neutralization of Special Elements in Output Used by a Downstream Component (Injection). CVSS score: 7.5/10. Published 2021-07-30.
How severe is CVE-2021-32558?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2021-32558 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.