Vulnerability record · CVE-2021-41157 · published 26 October 2021
CVE-2021-41157: Freeswitch improper authentication vulnerability
Freeswitch · Freeswitch
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.
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Affected products
1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.
References
| Link | Tags |
|---|---|
| http://seclists.org/fulldisclosure/2021/Oct/41 | Mailing ListThird Party Advisory |
| https://github.com/signalwire/freeswitch/commit/b21dd4e7f3a6f1d5f7be3ea500a319a5bc11db9e | PatchThird Party Advisory |
| https://github.com/signalwire/freeswitch/releases/tag/v1.10.6 | Release NotesThird Party Advisory |
| https://github.com/signalwire/freeswitch/security/advisories/GHSA-g7xg-7c54-rmpj | ExploitThird Party Advisory |
| http://seclists.org/fulldisclosure/2021/Oct/41 | Mailing ListThird Party Advisory |
| https://github.com/signalwire/freeswitch/commit/b21dd4e7f3a6f1d5f7be3ea500a319a5bc11db9e | PatchThird Party Advisory |
| https://github.com/signalwire/freeswitch/releases/tag/v1.10.6 | Release NotesThird Party Advisory |
| https://github.com/signalwire/freeswitch/security/advisories/GHSA-g7xg-7c54-rmpj | ExploitThird Party Advisory |
Track CVE-2021-41157 inside VULONE
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Related vulnerabilities
Same products first, then exploited flaws of the same weakness class.
Source: NIST National Vulnerability Database (record CVE-2021-41157), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.
