CVE-2021-41105Public exploitNetwork attack vector

Call termination via SRTP error-threshold exhaustion

Published Oct 25, 2021 · Updated Aug 4, 2024

Denial of service in SignalWire FreeSWITCH before 1.10.7 allows remote attackers to terminate active SRTP calls with crafted media packets. The SRTP receive path in switch_rtp.c hangs up a channel after unprotect errors reach the hard-coded MAX_SRTP_ERRS threshold of 100. No authentication or network foothold near either call participant is required, and a continuous UDP flood can repeatedly interrupt encrypted calls.

CVSS severity7.5
High
EPSS probability2.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in SignalWire FreeSWITCH before 1.10.7 allows remote attackers to terminate active SRTP calls with crafted media packets. The SRTP receive path in switch_rtp.c hangs up a channel after unprotect errors reach the hard-coded MAX_SRTP_ERRS threshold of 100. No authentication or network foothold near either call participant is required, and a continuous UDP flood can repeatedly interrupt encrypted calls.

The record

CVE
CVE-2021-41105
Published
Oct 25, 2021
Updated
Aug 4, 2024
Vendor
SignalWire
Product
FreeSWITCH
Classifications
CWE-20, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.10.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SignalWire · FreeSWITCHversion=< 1.10.7

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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