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Fencer Vulns
high 7.5

CVE-2021-37624 json

FreeSWITCH does not authenticate SIP MESSAGE requests, leading to spam and message spoofing

published 2021-10-25 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-24182

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
3.8%
EPSS 3.8% chance of exploitation in 30 days, percentile 90%
public exploits
0
none known

Summary

FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a software implementation that runs on any commodity hardware. Prior to version 1.10.7, FreeSWITCH does not authenticate SIP MESSAGE requests, leading to spam and message spoofing. By default, SIP requests of the type MESSAGE (RFC 3428) are not authenticated in the affected versions of FreeSWITCH. MESSAGE requests are relayed to SIP user agents registered with the FreeSWITCH server without requiring any authentication. Although this behaviour can be changed by setting the `auth-messages` parameter to `true`, it is not the default setting. Abuse of this security issue allows attackers to send SIP MESSAGE messages to any SIP user agent that is registered with the server without requiring authentication. Additionally, since no authentication is required, chat messages can be spoofed to appear to come from trusted entities. Therefore, abuse can lead to spam and enable social engineering, phishing and similar attacks. This issue is patched in version 1.10.7. Maintainers recommend that this SIP message type is authenticated by default so that FreeSWITCH administrators do not need to be explicitly set the `auth-messages` parameter. When following such a recommendation, a new parameter can be introduced to explicitly disable authentication.

Patch / fix

  • freeswitch freeswitch 1.10.7
  • freeswitch Alpine 3.24, Alpine 3.23, Alpine 3.22 +7 more 1.10.7-r0

alpine advisories ALPINE-CVE-2021-37624

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Exploit prediction

3.78% chance of exploitation in the next 30 days, higher than 90% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • packetstormsecurity.com http://packetstormsecurity.com/files/164628/FreeSWITCH-1.10.6-Missing-SIP-MESSAGE-Authentication.html referenced PoC, tagged "exploit" by a source, unverified
  • seclists.org http://seclists.org/fulldisclosure/2021/Oct/44 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N

Affected products

  • signalwire freeswitch

Classification

Weakness
  • CWE-287 Improper Authentication
  • CWE-306 Missing Authentication for Critical Functionality

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.