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No exploitation reportedFix available

CVE-2021-41158

No exploitation reported by the sources we read.

  • Published2021-10-26
  • Fixed in1.10.7
  • WeaknessCWE-200 · CWE-346

Am I affected?

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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. Prior to version 1.10.7, an attacker can perform a SIP digest leak attack against FreeSWITCH and receive the challenge response of a gateway configured on the FreeSWITCH server. This is done by challenging FreeSWITCH's SIP requests with the realm set to that of the gateway, thus forcing FreeSWITCH to respond with the challenge response which is based on the password of that targeted gateway. Abuse of this vulnerability allows attackers to potentially recover gateway passwords by performing a fast offline password cracking attack on the challenge response. The attacker does not require special network privileges, such as the ability to sniff the FreeSWITCH's network traffic, to exploit this issue. Instead, what is required for this attack to work is the ability to cause the victim server to send SIP request messages to the malicious party. Additionally, to exploit this issue, the attacker needs to specify the correct realm which might in some cases be considered secret. However, because many gateways are actually public, this information can easily be retrieved. The vulnerability appears to be due to the code which handles challenges in `sofia_reg.c`, `sofia_reg_handle_sip_r_challenge()` which does not check if the challenge is originating from the actual gateway. The lack of these checks allows arbitrary UACs (and gateways) to challenge any request sent by FreeSWITCH with the realm of the gateway being targeted. This issue is patched in version 10.10.7. Maintainers recommend that one should create an association between a SIP session for each gateway and its realm to make a check be put into place for this association when responding to challenges.

Timeline

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

Versions per branch

NVD
Freeswitch
BranchAffectedFixed in
1.10< 1.10.71.10.7

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 1.10.7

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 3.15.8known since 2026-10-23
  • NVDCVSS 3.17.5read 2026-10-23
  • NVDCVSS 2.05read 2026-10-23
  • CNAweakness (CWE)CWE-200known since 2026-10-23
  • NVDweakness (CWE)CWE-346read 2026-10-23
  • FIRST EPSSEPSS score0.8 %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:H/I:N/A:N
Published
2021-10-26
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2021-41158?

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, an attacker can perform a SIP digest leak attack against FreeSWITCH and receive the challenge response of a gateway configured on the FreeSWITCH server. This is done by challenging FreeSWITCH's SIP requests with the realm set to that of the gateway, thus forcing FreeSWITCH to respond with the challenge response which is based on the password of that targeted gateway. Abuse of this vulnerability allows attackers to potentially recover gateway passwords by performing a fast offline password cracking attack on the challenge response. The attacker does not require special network privileges, such as the ability to sniff the FreeSWITCH's network traffic, to exploit this issue. Instead, what is required for this attack to work is the ability to cause the victim server to send SIP request messages to the malicious party. Additionally, to exploit this issue, the attacker needs to specify the correct realm which might in some cases be considered secret. However, because many gateways are actually public, this information can easily be retrieved. The vulnerability appears to be due to the code which handles challenges in `sofia_reg.c`, `sofia_reg_handle_sip_r_challenge()` which does not check if the challenge is originating from the actual gateway. The lack of these checks allows arbitrary UACs (and gateways) to challenge any request sent by FreeSWITCH with the realm of the gateway being targeted. This issue is patched in version 10.10.7. Maintainers recommend that one should create an association between a SIP session for each gateway and its realm to make a check be put into place for this association when responding to challenges.

Is CVE-2021-41158 actively exploited?

Active exploitation of CVE-2021-41158 has not been confirmed. Its EPSS score was 0.8% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-41158?

CVE-2021-41158 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

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