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CVE-2023-49786

Asterisk susceptible to Denial of Service via DTLS Hello packets during call initiation

7.5 HighFix available

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

5.29%Up 5.2 points since Dec 15, 2023
90%50%10%1%

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 HighCVSS: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 HighCVSS: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 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1
5.9 MediumCVSS: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 MediumCVSS: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 HighCVSS: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 MediumCVSS: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 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.1
5.9 MediumCVSS: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

Affected packages
PackageAffectedFixed
asterisk
Alpine:v3.16
19.0.0 up to 18.20.2-r0
18.20.2-r0
asterisk
Alpine:v3.17
19.0.0 up to 18.20.2-r0
18.20.2-r0
asterisk
Alpine:v3.18
19.0.0 up to 18.20.2-r0
18.20.2-r0
asterisk
Alpine:v3.19
19.0.0 up to 20.5.1-r0
20.5.1-r0
asterisk
Alpine:v3.20
19.0.0 up to 20.5.1-r0
20.5.1-r0
asterisk
Alpine:v3.21
19.0.0 up to 20.5.1-r0
20.5.1-r0
asterisk
Alpine:v3.22
19.0.0 up to 20.5.1-r0
20.5.1-r0
asterisk
Alpine:v3.23
19.0.0 up to 20.5.1-r0
20.5.1-r0
asterisk
Alpine:v3.24
19.0.0 up to 20.5.1-r0
20.5.1-r0
asterisk
Debian: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
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1:1.0.6-21:1.0.7-11:1.0.7.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
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Affected packages
PackageAffectedFixed
asterisk
Debian: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
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1:16.16.1~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
asterisk
Debian: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
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1:16.16.1~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
asterisk
Ubuntu: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
asterisk
Ubuntu: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
asterisk
Ubuntu: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
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
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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
affected, facts
aliases, publishedEUVD
first indexedCVE 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

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Left out here: 218 versions. The JSON record has them.

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