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CVE-2021-26713

A stack-based buffer overflow in res_rtp_asterisk.c in Sangoma Asterisk before 16.16.1, 17.x...

6.5 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

1.87%Up 1.0 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 6.5

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.

Record
CVE-2021-26713
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
4.0 MediumAV:N/AC:L/Au:S/C:N/I:N/A:P
Weakness
CWE-787
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2021-26713
Updated
2026-11-02
EUVDEUVD-2021-13502 No score

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.

Record
EUVD-2021-13502
Updated
2026-11-03
GitHub AdvisoriesGHSA-24f6-gm96-3c56 No score

A stack-based buffer overflow in res_rtp_asterisk.c in Sangoma Asterisk before 16.16.1, 17.x...

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.

Record
GHSA-24f6-gm96-3c56
Weakness
CWE-787
Updated
2026-11-02
OSVALPINE-CVE-2021-26713 6.5

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.

Record
ALPINE-CVE-2021-26713
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSV 6.5

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.

Record
CVE-2021-26713
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-26713 6.5

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.

Record
UBUNTU-CVE-2021-26713
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
asterisk
Alpine:v3.12
 16.0.0 up to 16.16.1-r0
16.16.1-r0
asterisk
Alpine:v3.13
 16.0.0 up to 18.2.1-r0
18.2.1-r0
asterisk
Alpine:v3.14
 16.0.0 up to 18.2.1-r0
18.2.1-r0
asterisk
Alpine:v3.15
 16.0.0 up to 18.2.1-r0
18.2.1-r0
asterisk
Alpine:v3.16
 16.0.0 up to 18.2.1-r0
18.2.1-r0
asterisk
Alpine:v3.17
 16.0.0 up to 18.2.1-r0
18.2.1-r0
asterisk
Alpine:v3.18
 16.0.0 up to 18.2.1-r0
18.2.1-r0
asterisk
Alpine:v3.19
 16.0.0 up to 18.2.1-r0
18.2.1-r0
asterisk
Alpine:v3.20
 16.0.0 up to 18.2.1-r0
18.2.1-r0
asterisk
Alpine:v3.21
 16.0.0 up to 18.2.1-r0
18.2.1-r0
Show 8 moreShow less
Affected packages
PackageAffectedFixed
asterisk
Alpine:v3.22
 16.0.0 up to 18.2.1-r0
18.2.1-r0
asterisk
Alpine:v3.23
 16.0.0 up to 18.2.1-r0
18.2.1-r0
asterisk
Alpine:v3.24
 16.0.0 up to 18.2.1-r0
18.2.1-r0
asterisk
Ubuntu:22.04:LTS
 All versions, plus listed versions
1:16.16.1~dfsg-21:16.16.1~dfsg-41:16.16.1~dfsg-4build11:16.16.1~dfsg+~2.10-11:18.10.0~dfsg+~cs6.10.40431411-2
 None known
asterisk
Ubuntu:24.04:LTS
 All versions, plus listed versions
1:20.4.0~dfsg+~cs6.13.40431414-21:20.5.0~dfsg+~cs6.13.40431414-11:20.5.1~dfsg+~cs6.13.40431414-11:20.5.2~dfsg+~cs6.13.40431414-11:20.6.0~dfsg+~cs6.13.40431414-1
Show 4 moreShow less
1:20.6.0~dfsg+~cs6.13.40431414-21:20.6.0~dfsg+~cs6.13.40431414-2build31:20.6.0~dfsg+~cs6.13.40431414-2build41:20.6.0~dfsg+~cs6.13.40431414-2build5
 None known
asterisk
Ubuntu:25.10
 All versions, plus listed versions
1:22.2.0~dfsg+~cs6.15.60671435-21:22.3.0~dfsg+~cs6.15.60671435-11:22.4.1~dfsg+~cs6.15.60671435-11:22.4.1~dfsg+~cs6.15.60671435-21:22.5.1~dfsg+~cs6.15.60671435-11:22.5.2~dfsg+~cs6.15.60671435-1
 None known
asterisk
Ubuntu:26.10
 All versions, plus listed versions
1:22.5.2~dfsg+~cs6.15.60671435-11:22.10.0+dfsg+~cs6.17.60671434-1ubuntu21:22.10.0+dfsg+~cs6.17.60671434-1ubuntu3
 None known
asterisk
Ubuntu:26.04:LTS
 All versions, plus listed versions
1:22.5.2~dfsg+~cs6.15.60671435-1
 None known

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-26713 is a medium vulnerability (CVSS 6.5) in Digium Asterisk, published February 19, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.87%, the 79th percentile. Fixed in asterisk 16.16.1-r0.

References

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