No exploitation reportedFix available

CVE-2021-26712

Q: Is CVE-2021-26712 actively exploited?

Active exploitation of CVE-2021-26712 has not been confirmed. Its EPSS score was 3.6% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-26712?

CVE-2021-26712 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

No exploitation reported by the sources we read.

Published2021-02-18
Fixed in18.2.1 · 17.9.2 · 16.16.1

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Incorrect access controls in res_srtp.c in Sangoma Asterisk 13.38.1, 16.16.0, 17.9.1, and 18.2.0 and Certified Asterisk 16.8-cert5 allow a remote unauthenticated attacker to prematurely terminate secure calls by replaying SRTP packets.

Timeline

dates in UTC

2021-02-1821:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-26712?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-26712?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Digium asterisk

Branch	Affected	Fixed in	Source
18.x	≥ 18.0, < 18.2.1	18.2.1	NVD
17.x	≥ 17.0.0, < 17.9.2	17.9.2	NVD
16.x	≥ 16.0.0, < 16.16.1	16.16.1	NVD
13.x	≥ 13.0.0, ≤ 13.38.2	no fix published	NVD

Digium certified asterisk

Branch	Affected	Fixed in	Source
16.8	= 16.8	no fix published	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Digium asterisk to 18.2.1 · 17.9.2 · 16.16.1

Advisories and patches

downloads.asterisk.orgVendor Advisory
downloads.asterisk.orgVendor Advisory
issues.asterisk.orgPatch · Vendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.17.5read 2026-10-23
NVDCVSS 2.05read 2026-10-23
FIRST EPSSEPSS score3.6 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: 2021-02-18
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-26712?

Is CVE-2021-26712 actively exploited?

Active exploitation of CVE-2021-26712 has not been confirmed. Its EPSS score was 3.6% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-26712?

CVE-2021-26712 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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