CVE-2023-49786
Asterisk susceptible to Denial of Service via DTLS Hello packets during call initiation
Asterisk is an open source private branch exchange and telephony toolkit. In Asterisk prior to versions 18.20.1, 20.5.1, and 21.0.1; as well as certified-asterisk prior to 18.9-cert6; Asterisk is susceptible to a DoS due to a race condition in the hello handshake phase of the DTLS protocol when handling DTLS-SRTP for media setup. This attack can be done continuously, thus denying new DTLS-SRTP encrypted calls during the attack. Abuse of this vulnerability may lead to a massive Denial of Service on vulnerable Asterisk servers for calls that rely on DTLS-SRTP. Commit d7d7764cb07c8a1872804321302ef93bf62cba05 contains a fix, which is part of versions 18.20.1, 20.5.1, 21.0.1, amd 18.9-cert6.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
7.5
Asterisk susceptible to Denial of Service via DTLS Hello packets during call initiation
Asterisk is an open source private branch exchange and telephony toolkit. In Asterisk prior to versions 18.20.1, 20.5.1, and 21.0.1; as well as certified-asterisk prior to 18.9-cert6; Asterisk is susceptible to a DoS due to a race condition in the hello handshake phase of the DTLS protocol when handling DTLS-SRTP for media setup. This attack can be done continuously, thus denying new DTLS-SRTP encrypted calls during the attack. Abuse of this vulnerability may lead to a massive Denial of Service on vulnerable Asterisk servers for calls that rely on DTLS-SRTP. Commit d7d7764cb07c8a1872804321302ef93bf62cba05 contains a fix, which is part of versions 18.20.1, 20.5.1, 21.0.1, amd 18.9-cert6.
- Record
CVE-2023-49786- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-703
- Updated
- 2026-11-02
EUVDEUVD-2023-53705
7.5
Asterisk is an open source private branch exchange and telephony toolkit. In Asterisk prior to versions 18.20.1, 20.5.1, and 21.0.1; as well as certified-asterisk prior to 18.9-cert6; Asterisk is susceptible to a DoS due to a race condition in the hello handshake phase of the DTLS protocol when handling DTLS-SRTP for media setup. This attack can be done continuously, thus denying new DTLS-SRTP encrypted calls during the attack. Abuse of this vulnerability may lead to a massive Denial of Service on vulnerable Asterisk servers for calls that rely on DTLS-SRTP. Commit d7d7764cb07c8a1872804321302ef93bf62cba05 contains a fix, which is part of versions 18.20.1, 20.5.1, 21.0.1, amd 18.9-cert6.
- Record
EUVD-2023-53705- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
NVD
7.5
Asterisk is an open source private branch exchange and telephony toolkit. In Asterisk prior to versions 18.20.1, 20.5.1, and 21.0.1; as well as certified-asterisk prior to 18.9-cert6; Asterisk is susceptible to a DoS due to a race condition in the hello handshake phase of the DTLS protocol when handling DTLS-SRTP for media setup. This attack can be done continuously, thus denying new DTLS-SRTP encrypted calls during the attack. Abuse of this vulnerability may lead to a massive Denial of Service on vulnerable Asterisk servers for calls that rely on DTLS-SRTP. Commit d7d7764cb07c8a1872804321302ef93bf62cba05 contains a fix, which is part of versions 18.20.1, 20.5.1, 21.0.1, amd 18.9-cert6.
- Record
CVE-2023-49786- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - 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 - Weakness
- CWE-703, CWE-362
- Updated
- 2026-11-02
OSVALPINE-CVE-2023-49786
5.9
Asterisk is an open source private branch exchange and telephony toolkit. In Asterisk prior to versions 18.20.1, 20.5.1, and 21.0.1; as well as certified-asterisk prior to 18.9-cert6; Asterisk is susceptible to a DoS due to a race condition in the hello handshake phase of the DTLS protocol when handling DTLS-SRTP for media setup. This attack can be done continuously, thus denying new DTLS-SRTP encrypted calls during the attack. Abuse of this vulnerability may lead to a massive Denial of Service on vulnerable Asterisk servers for calls that rely on DTLS-SRTP. Commit d7d7764cb07c8a1872804321302ef93bf62cba05 contains a fix, which is part of versions 18.20.1, 20.5.1, 21.0.1, amd 18.9-cert6.
- Record
ALPINE-CVE-2023-49786- 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
7.5
Asterisk susceptible to Denial of Service via DTLS Hello packets during call initiation
Asterisk is an open source private branch exchange and telephony toolkit. In Asterisk prior to versions 18.20.1, 20.5.1, and 21.0.1; as well as certified-asterisk prior to 18.9-cert6; Asterisk is susceptible to a DoS due to a race condition in the hello handshake phase of the DTLS protocol when handling DTLS-SRTP for media setup. This attack can be done continuously, thus denying new DTLS-SRTP encrypted calls during the attack. Abuse of this vulnerability may lead to a massive Denial of Service on vulnerable Asterisk servers for calls that rely on DTLS-SRTP. Commit d7d7764cb07c8a1872804321302ef93bf62cba05 contains a fix, which is part of versions 18.20.1, 20.5.1, 21.0.1, amd 18.9-cert6.
- Record
CVE-2023-49786- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-703
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2023-49786
5.9
Asterisk is an open source private branch exchange and telephony toolkit. In Asterisk prior to versions 18.20.1, 20.5.1, and 21.0.1; as well as certified-asterisk prior to 18.9-cert6; Asterisk is susceptible to a DoS due to a race condition in the hello handshake phase of the DTLS protocol when handling DTLS-SRTP for media setup. This attack can be done continuously, thus denying new DTLS-SRTP encrypted calls during the attack. Abuse of this vulnerability may lead to a massive Denial of Service on vulnerable Asterisk servers for calls that rely on DTLS-SRTP. Commit d7d7764cb07c8a1872804321302ef93bf62cba05 contains a fix, which is part of versions 18.20.1, 20.5.1, 21.0.1, amd 18.9-cert6.
- Record
DEBIAN-CVE-2023-49786- 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
OSVUBUNTU-CVE-2023-49786
7.5
Asterisk is an open source private branch exchange and telephony toolkit. In Asterisk prior to versions 18.20.1, 20.5.1, and 21.0.1; as well as certified-asterisk prior to 18.9-cert6; Asterisk is susceptible to a DoS due to a race condition in the hello handshake phase of the DTLS protocol when handling DTLS-SRTP for media setup. This attack can be done continuously, thus denying new DTLS-SRTP encrypted calls during the attack. Abuse of this vulnerability may lead to a massive Denial of Service on vulnerable Asterisk servers for calls that rely on DTLS-SRTP. Commit d7d7764cb07c8a1872804321302ef93bf62cba05 contains a fix, which is part of versions 18.20.1, 20.5.1, 21.0.1, amd 18.9-cert6.
- Record
UBUNTU-CVE-2023-49786- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - 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:v3.16 |
19.0.0 up to 18.20.2-r0 | 18.20.2-r0 |
asteriskAlpine:v3.17 |
19.0.0 up to 18.20.2-r0 | 18.20.2-r0 |
asteriskAlpine:v3.18 |
19.0.0 up to 18.20.2-r0 | 18.20.2-r0 |
asteriskAlpine:v3.19 |
19.0.0 up to 20.5.1-r0 | 20.5.1-r0 |
asteriskAlpine:v3.20 |
19.0.0 up to 20.5.1-r0 | 20.5.1-r0 |
asteriskAlpine:v3.21 |
19.0.0 up to 20.5.1-r0 | 20.5.1-r0 |
asteriskAlpine:v3.22 |
19.0.0 up to 20.5.1-r0 | 20.5.1-r0 |
asteriskAlpine:v3.23 |
19.0.0 up to 20.5.1-r0 | 20.5.1-r0 |
asteriskAlpine:v3.24 |
19.0.0 up to 20.5.1-r0 | 20.5.1-r0 |
asteriskDebian:14 |
before 1:20.5.1~dfsg+~cs6.13.40431414-1, 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 |
1:20.5.1~dfsg+~cs6.13.40431414-1 |
Show 10 moreShow less
| Package | Affected | Fixed |
|---|---|---|
asteriskDebian:10 From an advisory covering 4 CVEs |
before 1:16.28.0~dfsg-0+deb10u4, plus listed versions 1:16.10.0~dfsg-11:16.12.0~dfsg-11:16.15.0~dfsg-11:16.15.1~dfsg-11:16.16.1~dfsg+~2.10-1 Show 17 moreShow less1:16.16.1~dfsg+~2.10-21:16.16.1~dfsg-11:16.16.1~dfsg-1~bpo10+11:16.16.1~dfsg-21:16.16.1~dfsg-31:16.16.1~dfsg-41:16.2.1~dfsg-11:16.2.1~dfsg-1+deb10u11:16.2.1~dfsg-1+deb10u21:16.2.1~dfsg-21:16.23.0~dfsg+~2.10-11:16.23.0~dfsg+~cs6.10.20220309-11:16.23.0~dfsg+~cs6.10.20220309-21:16.23.0~dfsg+~cs6.10.40431411-11:16.28.0~dfsg-0+deb10u11:16.28.0~dfsg-0+deb10u21:16.28.0~dfsg-0+deb10u3 |
1:16.28.0~dfsg-0+deb10u4 |
asteriskDebian:11 From an advisory covering 4 CVEs |
before 1:16.28.0~dfsg-0+deb11u4, plus listed versions 1:16.16.1~dfsg+~2.10-11:16.16.1~dfsg+~2.10-21:16.16.1~dfsg-11:16.16.1~dfsg-1+deb11u11:16.16.1~dfsg-1+deb11u1~bpo10+1 Show 10 moreShow less1:16.16.1~dfsg-21:16.16.1~dfsg-31:16.16.1~dfsg-41:16.23.0~dfsg+~2.10-11:16.23.0~dfsg+~cs6.10.20220309-11:16.23.0~dfsg+~cs6.10.20220309-21:16.23.0~dfsg+~cs6.10.40431411-11:16.28.0~dfsg-0+deb11u11:16.28.0~dfsg-0+deb11u21:16.28.0~dfsg-0+deb11u3 |
1:16.28.0~dfsg-0+deb11u4 |
asteriskUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 1:13.1.0~dfsg-1.1ubuntu31:13.1.0~dfsg-1.1ubuntu41:13.1.0~dfsg-1.1ubuntu4.11:13.1.0~dfsg-1.1ubuntu4.1+esm1 |
None known |
asteriskUbuntu:18.04:LTS |
All versions, plus listed versions 1:13.17.2~dfsg-1ubuntu11:13.17.2~dfsg-2ubuntu11:13.18.1~dfsg-1ubuntu11:13.18.3~dfsg-1ubuntu11:13.18.3~dfsg-1ubuntu21:13.18.3~dfsg-1ubuntu31:13.18.3~dfsg-1ubuntu4 |
None known |
asteriskUbuntu:20.04:LTS |
All versions, plus listed versions 1:16.2.1~dfsg-2build21:16.2.1~dfsg-2build31:16.2.1~dfsg-2ubuntu1 |
None known |
asteriskUbuntu: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 |
asteriskUbuntu: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 less1:20.6.0~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 |
asteriskUbuntu: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 |
asteriskUbuntu: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 |
asteriskUbuntu:26.04:LTS |
All versions, plus listed versions 1:22.5.2~dfsg+~cs6.15.60671435-1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| aliases, published | EUVD | |
| first indexed | CVE List, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-49786 is a high vulnerability (CVSS 7.5) in Asterisk, published December 14, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 5.29%, the 92nd percentile. Fixed in asterisk 18.20.2-r0.
References
github.com/asterisk/asterisk/security/advisories/GHSA-hxj9-xwr8-w8pq
github.com/asterisk/asterisk/commit/d7d7764cb07c8a1872804321302ef93bf62cba05
github.com/EnableSecurity/advisories/tree/master/ES2023-01-asterisk-dtls-hello-race
openwall.com/lists/oss-security/2023/12/15/7
packetstormsecurity.com/files/176251/Asterisk-20.1.0-Denial-Of-Service.html
seclists.org/fulldisclosure/2023/Dec/24
Show 7 moreShow less
lists.debian.org/debian-lts-announce/2023/12/msg00019.html
security.alpinelinux.org/vuln/CVE-2023-49786
github.com/CVEProject/cvelistV5/tree/main/cves/2023/49xxx/CVE-2023-49786.json
nvd.nist.gov/vuln/detail/CVE-2023-49786
security-tracker.debian.org/tracker/CVE-2023-49786
ubuntu.com/security/CVE-2023-49786
cve.org/CVERecord?id=CVE-2023-49786
Left out here: 218 versions. The JSON record has them.