CVE-2021-37624Public exploitNetwork attack vector

Message spoofing via unauthenticated SIP MESSAGE relay

Published Oct 25, 2021 · Updated Aug 4, 2024

Improper authentication in SignalWire FreeSWITCH 1.10.6 and earlier allows remote attackers to spoof chat messages via SIP MESSAGE requests. The mod_sofia SIP profile relays inbound MESSAGE requests to registered user agents without requiring digest authentication because auth-messages is disabled by default. An exposed SIP profile and a registered MESSAGE-capable recipient are required; successful abuse delivers attacker-chosen messages that appear to come from trusted senders.

CVSS severity7.5
High
EPSS probability3.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in SignalWire FreeSWITCH 1.10.6 and earlier allows remote attackers to spoof chat messages via SIP MESSAGE requests. The mod_sofia SIP profile relays inbound MESSAGE requests to registered user agents without requiring digest authentication because auth-messages is disabled by default. An exposed SIP profile and a registered MESSAGE-capable recipient are required; successful abuse delivers attacker-chosen messages that appear to come from trusted senders.

The record

CVE
CVE-2021-37624
Published
Oct 25, 2021
Updated
Aug 4, 2024
Vendor
SignalWire
Product
FreeSWITCH
Classifications
CWE-287, T1566.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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=< 1.10.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SignalWire · FreeSWITCHversion=< 1.10.7

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

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.

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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-287Improper Authentication
T1566.003Spearphishing via Service

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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