CVE-2023-49786Public exploitNetwork attack vector

Call interruption via unvalidated DTLS ClientHello

Published Dec 14, 2023 · Updated Feb 13, 2025

Race condition in Asterisk before 18.20.1, 19.0.0 through 20.5.0, and 21.0.0 allows remote attackers to interrupt DTLS-SRTP calls. The RTP receive path accepts DTLS ClientHello packets before ICE validates the sender; an invalid cipher error tears down the media session and its SIP signaling. Network access to the RTP UDP port range and an active call using DTLS-SRTP are required, and repeated packets can deny new encrypted calls.

CVSS severity5.9
Medium
EPSS probability5.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Asterisk before 18.20.1, 19.0.0 through 20.5.0, and 21.0.0 allows remote attackers to interrupt DTLS-SRTP calls. The RTP receive path accepts DTLS ClientHello packets before ICE validates the sender; an invalid cipher error tears down the media session and its SIP signaling. Network access to the RTP UDP port range and an active call using DTLS-SRTP are required, and repeated packets can deny new encrypted calls.

The record

CVE
CVE-2023-49786
Published
Dec 14, 2023
Updated
Feb 13, 2025
Vendor
Asterisk
Product
Asterisk
Classifications
CWE-362, CWE-703, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 14, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 18.20.1
  2. Affected versionversion=< 18.9-cert6
  3. Affected versionversion=>= 19.0.0, < 20.5.1
  4. Affected versionversion== 21.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Asterisk · Asteriskversion=< 18.20.1; version=< 18.9-cert6; version=>= 19.0.0, < 20.5.1; version== 21.0.0

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-703Improper Check or Handling of Exceptional Conditions
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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