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Freeswitch CVE-2021-37624

HIGH
Improper Authentication (CWE-287)
2021-10-25 security-advisories@github.com
7.5
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V6 - Authentication Authentication mechanism validation
MITRE ATT&CK

2 techniques across 2 tactics: Defense Evasion, Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 7.5 (HIGH). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available.

Exploit ScenarioDerived

A remote attacker could bypass authentication mechanisms to gain unauthorized access by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 3.5% exploitation probability (EPSS)

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AnalysisAI

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. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Implement multi-factor authentication, enforce strong password policies, use proven authentication frameworks.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Improper Authentication (CWE-287), which allows attackers to bypass authentication mechanisms to gain unauthorized access. 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. Affected products include: Freeswitch. Version information: version 1.10.7.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

DescriptionNVD

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.

Threat Intelligence Overview

EPSS Score
3.5%
Top 12% exploitable
Exploit
POC
Public exploit code exists
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC Yes
EPSS 3.5%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

62
Low Medium High Critical
KEV: 0
EPSS: +4
CVSS: +38
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Affected Products (CPE)NVD

cpe:2.3:a:freeswitch:freeswitch:*:*:*:*:*:*:*:*
CVE-2019-19492 CRITICAL POC
9.8 Dec 02

FreeSWITCH 1.6.10 through 1.10.1 has a default password in event_socket.conf.xml. Rated critical severity (CVSS 9.8), th

CVE-2015-7392 HIGH POC
7.5 Oct 05

Heap-based buffer overflow in the parse_string function in libs/esl/src/esl_json.c in FreeSWITCH before 1.4.23 and 1.6.x

CVE-2021-41158 HIGH POC
7.5 Oct 26

FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to

CVE-2021-41145 HIGH POC
7.5 Oct 25

FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to

CVE-2021-41105 HIGH POC
7.5 Oct 25

FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to

CVE-2021-36513 HIGH POC
7.5 Oct 18

An issue was discovered in function sofia_handle_sip_i_notify in sofia.c in SignalWire freeswitch before 1.10.6, may all

CVE-2018-19911 HIGH POC
7.5 Dec 06

FreeSWITCH through 1.8.2, when mod_xml_rpc is enabled, allows remote attackers to execute arbitrary commands via the api

CVE-2013-2238 MEDIUM POC
6.8 Sep 30

Multiple buffer overflows in the switch_perform_substitution function in switch_regex.c in FreeSWITCH 1.2 allow remote a

CVE-2026-110658 MEDIUM POC
6.9 Oct 14

Heap out-of-bounds read in Sofia-SIP through 1.13.18 allows unauthenticated remote attackers to crash SIP processes by s

CVE-2023-40019 MEDIUM POC
6.5 Sep 15

FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to

CVE-2023-51443 MEDIUM POC
5.9 Dec 27

FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to

CVE-2026-49841 CRITICAL
9.8 Jun 09

Heap buffer overflow in FreeSWITCH mod_verto prior to version 1.11.1 allows remote unauthenticated attackers to corrupt

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