CVE-2021-26906
An issue was discovered in res_pjsip_session.c in Digium Asterisk through 13.38.1; 14.x, 15.x,...
An issue was discovered in res_pjsip_session.c in Digium Asterisk through 13.38.1; 14.x, 15.x, and 16.x through 16.16.0; 17.x through 17.9.1; and 18.x through 18.2.0, and Certified Asterisk through 16.8-cert5. An SDP negotiation vulnerability in PJSIP allows a remote server to potentially crash Asterisk by sending specific SIP responses that cause an SDP negotiation failure.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
An issue was discovered in res_pjsip_session.c in Digium Asterisk through 13.38.1; 14.x, 15.x, and 16.x through 16.16.0; 17.x through 17.9.1; and 18.x through 18.2.0, and Certified Asterisk through 16.8-cert5. An SDP negotiation vulnerability in PJSIP allows a remote server to potentially crash Asterisk by sending specific SIP responses that cause an SDP negotiation failure.
- Record
CVE-2021-26906- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 4.3 Medium
AV:N/AC:M/Au:N/C:N/I:N/A:P - Weakness
- CWE-404
- Updated
- 2026-11-02
CVE List No score
An issue was discovered in res_pjsip_session.c in Digium Asterisk through 13.38.1; 14.x, 15.x, and 16.x through 16.16.0; 17.x through 17.9.1; and 18.x through 18.2.0, and Certified Asterisk through 16.8-cert5. An SDP negotiation vulnerability in PJSIP allows a remote server to potentially crash Asterisk by sending specific SIP responses that cause an SDP negotiation failure.
- Record
CVE-2021-26906- Updated
- 2026-11-02
EUVDEUVD-2021-13690 No score
An issue was discovered in res_pjsip_session.c in Digium Asterisk through 13.38.1; 14.x, 15.x, and 16.x through 16.16.0; 17.x through 17.9.1; and 18.x through 18.2.0, and Certified Asterisk through 16.8-cert5. An SDP negotiation vulnerability in PJSIP allows a remote server to potentially crash Asterisk by sending specific SIP responses that cause an SDP negotiation failure.
- Record
EUVD-2021-13690- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-rjqf-qvfr-v23c No score
An issue was discovered in res_pjsip_session.c in Digium Asterisk through 13.38.1; 14.x, 15.x,...
An issue was discovered in res_pjsip_session.c in Digium Asterisk through 13.38.1; 14.x, 15.x, and 16.x through 16.16.0; 17.x through 17.9.1; and 18.x through 18.2.0, and Certified Asterisk through 16.8-cert5. An SDP negotiation vulnerability in PJSIP allows a remote server to potentially crash Asterisk by sending specific SIP responses that cause an SDP negotiation failure.
- Record
GHSA-rjqf-qvfr-v23c- Weakness
- CWE-404
- Updated
- 2026-11-02
OSVALPINE-CVE-2021-26906
An issue was discovered in res_pjsip_session.c in Digium Asterisk through 13.38.1; 14.x, 15.x, and 16.x through 16.16.0; 17.x through 17.9.1; and 18.x through 18.2.0, and Certified Asterisk through 16.8-cert5. An SDP negotiation vulnerability in PJSIP allows a remote server to potentially crash Asterisk by sending specific SIP responses that cause an SDP negotiation failure.
- Record
ALPINE-CVE-2021-26906- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSV
An issue was discovered in res_pjsip_session.c in Digium Asterisk through 13.38.1; 14.x, 15.x, and 16.x through 16.16.0; 17.x through 17.9.1; and 18.x through 18.2.0, and Certified Asterisk through 16.8-cert5. An SDP negotiation vulnerability in PJSIP allows a remote server to potentially crash Asterisk by sending specific SIP responses that cause an SDP negotiation failure.
- Record
CVE-2021-26906- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVDEBIAN-CVE-2021-26906
An issue was discovered in res_pjsip_session.c in Digium Asterisk through 13.38.1; 14.x, 15.x, and 16.x through 16.16.0; 17.x through 17.9.1; and 18.x through 18.2.0, and Certified Asterisk through 16.8-cert5. An SDP negotiation vulnerability in PJSIP allows a remote server to potentially crash Asterisk by sending specific SIP responses that cause an SDP negotiation failure.
- Record
DEBIAN-CVE-2021-26906- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
asteriskAlpine:v3.12 |
13.0.0 up to 16.16.1-r0 | 16.16.1-r0 |
asteriskAlpine:v3.13 |
13.0.0 up to 18.2.1-r0 | 18.2.1-r0 |
asteriskAlpine:v3.14 |
13.0.0 up to 18.2.1-r0 | 18.2.1-r0 |
asteriskAlpine:v3.15 |
13.0.0 up to 18.2.1-r0 | 18.2.1-r0 |
asteriskAlpine:v3.16 |
13.0.0 up to 18.2.1-r0 | 18.2.1-r0 |
asteriskAlpine:v3.17 |
13.0.0 up to 18.2.1-r0 | 18.2.1-r0 |
asteriskAlpine:v3.18 |
13.0.0 up to 18.2.1-r0 | 18.2.1-r0 |
asteriskAlpine:v3.19 |
13.0.0 up to 18.2.1-r0 | 18.2.1-r0 |
asteriskAlpine:v3.20 |
13.0.0 up to 18.2.1-r0 | 18.2.1-r0 |
asteriskAlpine:v3.21 |
13.0.0 up to 18.2.1-r0 | 18.2.1-r0 |
Show 4 moreShow less
| Package | Affected | Fixed |
|---|---|---|
asteriskAlpine:v3.22 |
13.0.0 up to 18.2.1-r0 | 18.2.1-r0 |
asteriskAlpine:v3.23 |
13.0.0 up to 18.2.1-r0 | 18.2.1-r0 |
asteriskAlpine:v3.24 |
13.0.0 up to 18.2.1-r0 | 18.2.1-r0 |
asteriskDebian:14 |
before 1:16.16.1~dfsg-1, plus listed versions 0.1.11-30.1.11-3woody11:1.0.5-21:1.0.5-41:1.0.6-1 Show 45 moreShow less1:1.0.6-21:1.0.7-11:1.0.7.dfsg.1-11:1.0.7.dfsg.1-21:1.0.7.dfsg.1-2sarge11:1.0.7.dfsg.1-2sarge21:1.0.7.dfsg.1-2sarge31:1.0.7.dfsg.1-2sarge41:1.0.7.dfsg.1-2sarge51:1.0.7.dfsg.1-2sarge61:1.0.9.dfsg-11:1.0.9.dfsg-31:1.0.9.dfsg-41:1.0.9.dfsg-51:1.0.9.dfsg-61:1.2.0-beta1.dfsg-11:1.2.0-beta2.dfsg-11:1.2.0-beta2.dfsg-21:1.2.0-beta2.dfsg-31:1.2.0-rc1.dfsg-11:1.2.0-rc2.dfsg-11:1.2.0.dfsg-11:1.2.0.dfsg-21:1.2.0.dfsg-31:1.2.0.dfsg-41:1.2.0.dfsg-51:1.2.0.dfsg-61:1.2.1.dfsg-11:1.2.1.dfsg-21:1.2.1.dfsg-31:1.2.10.dfsg-11:1.2.10.dfsg-1bpo11:1.2.10.dfsg-21:1.2.10.dfsg-31:1.2.11.dfsg-11:1.2.12.1.dfsg-11:1.2.13~dfsg-11:1.2.13~dfsg-21:1.2.13~dfsg-2etch11:1.2.13~dfsg-2etch21:1.2.13~dfsg-2etch31:1.2.13~dfsg-2etch41:1.2.14~dfsg-11:1.2.14~dfsg-21:1.2.14~dfsg-3 |
1:16.16.1~dfsg-1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-26906 is a medium vulnerability (CVSS 5.9) in Digium Asterisk, published February 18, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.55%, the 85th percentile. Fixed in asterisk 16.16.1-r0.
References
downloads.asterisk.org/pub/security
seclists.org/fulldisclosure/2021/Feb/61
issues.asterisk.org/jira/browse/ASTERISK-29196
packetstormsecurity.com/files/161477/Asterisk-Project-Security-Advisory-AST-2021-005.html
nvd.nist.gov/vuln/detail/CVE-2021-26906
github.com/advisories/GHSA-rjqf-qvfr-v23c
security.alpinelinux.org/vuln/CVE-2021-26906
security-tracker.debian.org/tracker/CVE-2021-26906
Left out here: 187 versions. The JSON record has them.