CVE-2021-41157

FreeSWITCH does not authenticate SIP SUBSCRIBE requests by default

MEDIUM
5.3
CVSS Score
Published: October 26, 2021 at 01:35 PM UTC
Updated: June 17, 2026 at 04:07 AM UTC
2 products affected across 2 vendorsFreeswitchFreeswitch

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Severity
MEDIUM5.3
Exploit prediction
EPSS 2%

Description

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. By default, SIP requests of the type SUBSCRIBE are not authenticated in the affected versions of FreeSWITCH. Abuse of this security issue allows attackers to subscribe to user agent event notifications without the need to authenticate. This abuse poses privacy concerns and might lead to social engineering or similar attacks. For example, attackers may be able to monitor the status of target SIP extensions. Although this issue was fixed in version v1.10.6, installations upgraded to the fixed version of FreeSWITCH from an older version, may still be vulnerable if the configuration is not updated accordingly. Software upgrades do not update the configuration by default. SIP SUBSCRIBE messages should be authenticated by default so that FreeSWITCH administrators do not need to explicitly set the `auth-subscriptions` parameter. When following such a recommendation, a new parameter can be introduced to explicitly disable authentication.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.10.6
Affected range stops below 1.10.6, so it looks safe — our inference, not a vendor statement
v < 1.10.6
Affected range stops below 1.10.6, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

CVSS

5.3MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-287CWE-306

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