A stack-based buffer overflow in res_rtp_asterisk.c in Sangoma Asterisk before 16.16.1…
Priority LOW 33CWE-787Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-787 and the CVSS impact.
Summary
A stack-based buffer overflow in res_rtp_asterisk.c in Sangoma Asterisk before 16.16.1, 17.x before 17.9.2, and 18.x before 18.2.1 and Certified Asterisk before 16.8-cert6 allows an authenticated WebRTC client to cause an Asterisk crash by sending multiple hold/unhold requests in quick succession. This is caused by a signedness comparison mismatch.
Why it matters now
EPSS 0.01868 79th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 14
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:digium:asterisk:*:*:*:*:*:*:*:* | 16.0.0 to before 16.16.1; 17.0.0 to before 17.9.2; 18.0.0 to before 18.2.1 | Vulnerable | Digium |
| cpe:2.3:a:digium:certified_asterisk:16.8:-:*:*:*:*:*:* | 16.8 | Vulnerable | Digium |
| cpe:2.3:a:digium:certified_asterisk:16.8:cert1-rc1:*:*:*:*:*:* | 16.8 cert1-rc1 | Vulnerable | Digium |
| cpe:2.3:a:digium:certified_asterisk:16.8:cert1-rc2:*:*:*:*:*:* | 16.8 cert1-rc2 | Vulnerable | Digium |
| cpe:2.3:a:digium:certified_asterisk:16.8:cert1-rc3:*:*:*:*:*:* | 16.8 cert1-rc3 | Vulnerable | Digium |
| cpe:2.3:a:digium:certified_asterisk:16.8:cert1-rc4:*:*:*:*:*:* | 16.8 cert1-rc4 | Vulnerable | Digium |
| cpe:2.3:a:digium:certified_asterisk:16.8:cert2:*:*:*:*:*:* | 16.8 cert2 | Vulnerable | Digium |
| cpe:2.3:a:digium:certified_asterisk:16.8:cert3:*:*:*:*:*:* | 16.8 cert3 | Vulnerable | Digium |
| cpe:2.3:a:digium:certified_asterisk:16.8:cert4:*:*:*:*:*:* | 16.8 cert4 | Vulnerable | Digium |
| cpe:2.3:a:digium:certified_asterisk:16.8:cert4-rc1:*:*:*:*:*:* | 16.8 cert4-rc1 | Vulnerable | Digium |
- cpe:2.3:a:digium:asterisk:*:*:*:*:*:*:*:* Versions 16.0.0 to before 16.16.1; 17.0.0 to before 17.9.2; 18.0.0 to before 18.2.1 Vulnerable ·Digium
- cpe:2.3:a:digium:certified_asterisk:16.8:-:*:*:*:*:*:* Versions 16.8 Vulnerable ·Digium
- cpe:2.3:a:digium:certified_asterisk:16.8:cert1-rc1:*:*:*:*:*:* Versions 16.8 cert1-rc1 Vulnerable ·Digium
- cpe:2.3:a:digium:certified_asterisk:16.8:cert1-rc2:*:*:*:*:*:* Versions 16.8 cert1-rc2 Vulnerable ·Digium
- cpe:2.3:a:digium:certified_asterisk:16.8:cert1-rc3:*:*:*:*:*:* Versions 16.8 cert1-rc3 Vulnerable ·Digium
- cpe:2.3:a:digium:certified_asterisk:16.8:cert1-rc4:*:*:*:*:*:* Versions 16.8 cert1-rc4 Vulnerable ·Digium
- cpe:2.3:a:digium:certified_asterisk:16.8:cert2:*:*:*:*:*:* Versions 16.8 cert2 Vulnerable ·Digium
- cpe:2.3:a:digium:certified_asterisk:16.8:cert3:*:*:*:*:*:* Versions 16.8 cert3 Vulnerable ·Digium
- cpe:2.3:a:digium:certified_asterisk:16.8:cert4:*:*:*:*:*:* Versions 16.8 cert4 Vulnerable ·Digium
- cpe:2.3:a:digium:certified_asterisk:16.8:cert4-rc1:*:*:*:*:*:* Versions 16.8 cert4-rc1 Vulnerable ·Digium
Show 4 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:digium:certified_asterisk:16.8:cert4-rc2:*:*:*:*:*:* | 16.8 cert4-rc2 | Vulnerable | Digium |
| cpe:2.3:a:digium:certified_asterisk:16.8:cert4-rc3:*:*:*:*:*:* | 16.8 cert4-rc3 | Vulnerable | Digium |
| cpe:2.3:a:digium:certified_asterisk:16.8:cert4-rc4:*:*:*:*:*:* | 16.8 cert4-rc4 | Vulnerable | Digium |
| cpe:2.3:a:digium:certified_asterisk:16.8:cert5:*:*:*:*:*:* | 16.8 cert5 | Vulnerable | Digium |
- cpe:2.3:a:digium:certified_asterisk:16.8:cert4-rc2:*:*:*:*:*:* Versions 16.8 cert4-rc2 Vulnerable ·Digium
- cpe:2.3:a:digium:certified_asterisk:16.8:cert4-rc3:*:*:*:*:*:* Versions 16.8 cert4-rc3 Vulnerable ·Digium
- cpe:2.3:a:digium:certified_asterisk:16.8:cert4-rc4:*:*:*:*:*:* Versions 16.8 cert4-rc4 Vulnerable ·Digium
- cpe:2.3:a:digium:certified_asterisk:16.8:cert5:*:*:*:*:*:* Versions 16.8 cert5 Vulnerable ·Digium
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2021-26713
- 2026-10-03 Alias added: GHSA-24f6-gm96-3c56
References
More Digium Asterisk vulnerabilities
- TI-2006-05256 Integer overflow in the get_input function in the Skinny channel driver (chan_skinny.c)… CVSS 2.0HIGH 7.5
- TI-2017-12542 An issue was discovered in chan_skinny.c in Asterisk Open Source 13.18.2 and older… CVSS 3.0HIGH 7.5
- TI-2023-27195 Asterisk susceptible to Denial of Service via DTLS Hello packets during call initiation CVSS 3.1HIGH 7.5
- TI-2017-13083 An issue was discovered in Asterisk 13.18.4 and older, 14.7.4 and older, 15.1.4 and… CVSS 3.0HIGH 7.5
- TI-2019-13459 An issue was discovered in manager.c in Sangoma Asterisk through 13.x, 16.x, 17.x and… CVSS 3.1HIGH 8.8
- TI-2018-05283 A Buffer Overflow issue was discovered in Asterisk through 13.19.1, 14.x through 14.7.5… CVSS 3.0HIGH 7.5
Sources
- CVE-2021-26713 · CVE Program
- CVE-2021-26713 · NVD
- FIRST EPSS
- GHSA-24f6-gm96-3c56 · GitHub Advisory Database · CC BY 4.0
- CVE-2021-26713 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences