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No exploitation reportedFix available

CVE-2021-41157

No exploitation reported by the sources we read.

  • Published2021-10-26
  • Fixed in1.10.6
  • WeaknessCWE-287 · CWE-306

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2021-10-2614:15CVE publishedNVD

Versions per branch

NVD
Freeswitch
BranchAffectedFixed in
1.10< 1.10.61.10.6

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • freeswitchCleanStartall versions · fixed in 1.10.7-r0
  • freeswitchAlpine:v3.24all versions · fixed in 1.10.7-r0
  • freeswitchAlpine:v3.23all versions · fixed in 1.10.7-r0
  • freeswitchAlpine:v3.22all versions · fixed in 1.10.7-r0
  • freeswitchAlpine:v3.21all versions · fixed in 1.10.7-r0
  • freeswitchAlpine:v3.20all versions · fixed in 1.10.7-r0
  • freeswitchAlpine:v3.19all versions · fixed in 1.10.7-r0
  • freeswitchAlpine:v3.18all versions · fixed in 1.10.7-r0

3 more package ranges on OSV.dev

Full record on NVD

Fix

  1. Update Freeswitch to 1.10.6

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • CNACVSS 3.15.3known since 2026-10-23
  • NVDCVSS 2.05read 2026-10-23
  • CNAweakness (CWE)CWE-287known since 2026-10-23
  • NVDweakness (CWE)CWE-306read 2026-10-23
  • FIRST EPSSEPSS score1.7 %2026-11-08
  • OSVaffected packages—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Published
2021-10-26
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2021-41157?

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.

Is CVE-2021-41157 actively exploited?

Active exploitation of CVE-2021-41157 has not been confirmed. Its EPSS score was 1.7% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-41157?

CVE-2021-41157 has a CVSS v3 base score of 5.3 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

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