VulnerabilityPublished 27 Dec 2023Updated 4 Nov 2025

CVE-2023-51443: signalwire freeswitch · Improper Check or Handling of Exceptional Conditions

Affects signalwire freeswitchSource CVE Database V5

Not known to be exploited · CVSS 7.5 High : upgrade to 1.10.11 soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 1.4% chance of exploitation in 30 days – higher than 73% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.10.11

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 27 Dec 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade signalwire/freeswitch to 1.10.11.

Affected software

Product	Affected	Fixed in
GitHubsignalwire/freeswitch`pkg:github/signalwire/freeswitch`Other threats	Affected <1.10.11	Fixed in 1.10.11

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

The primary mitigation is to upgrade all FreeSWITCH deployments to version 1.10.11 or later, which includes the security fix that drops packets from unvalidated IP addresses after ICE checks. Organizations should implement strict network-level filtering to block malformed or suspicious DTLS ClientHello messages, particularly those with invalid CipherSuites. Monitoring and alerting on abnormal DTLS handshake failures can help detect ongoing exploitation attempts. Deploying rate limiting on DTLS handshake requests can reduce the impact of flooding attacks. It is also advisable to review and harden ICE configuration to ensure only validated addresses are accepted. For environments where immediate upgrade is not feasible, isolating FreeSWITCH servers behind firewalls or session border controllers (SBCs) that can filter DTLS traffic is recommended. Regular vulnerability scanning and penetration testing should include checks for this vulnerability. Finally, maintaining up-to-date incident response plans for telecom service disruptions will help minimize downtime if exploitation occurs.

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 1.10.11, when handling DTLS-SRTP for media setup, FreeSWITCH is susceptible to Denial of Service due to a race condition in the hello handshake phase of the DTLS protocol. This attack can be done continuously, thus denying new DTLS-SRTP encrypted calls during the attack. If an attacker manages to send a ClientHello DTLS message with an invalid CipherSuite (such as `TLS_NULL_WITH_NULL_NULL`) to the port on the FreeSWITCH server that is expecting packets from the caller, a DTLS error is generated. This results in the media session being torn down, which is followed by teardown at signaling (SIP) level too. Abuse of this vulnerability may lead to a massive Denial of Service on vulnerable FreeSWITCH servers for calls that rely on DTLS-SRTP. To address this vulnerability, upgrade FreeSWITCH to 1.10.11 which includes the security fix. The solution implemented is to drop all packets from addresses that have not been validated by an ICE check.

Impact

For European organizations, especially telecom providers, VoIP service operators, and enterprises using FreeSWITCH for secure communications, this vulnerability poses a substantial risk of service disruption. The ability to continuously deny new encrypted calls can lead to significant operational outages, impacting business communications, customer service, and emergency response capabilities. Since the attack targets the media layer and causes signaling teardown, it can degrade call quality and availability, potentially affecting large user bases. The disruption of DTLS-SRTP encrypted calls also undermines trust in secure communication channels. In regulated sectors such as finance, healthcare, and government, such outages could lead to compliance issues and reputational damage. Additionally, the ease of exploitation without authentication increases the threat from opportunistic attackers or competitors. The economic impact could be considerable due to lost productivity and remediation costs. Organizations relying on FreeSWITCH in multi-tenant or cloud environments may experience cascading effects impacting multiple customers or services.

Summary

CVE-2023-51443 is a vulnerability in FreeSWITCH, an open-source software-defined telecom stack widely used for VoIP and telecom services. The flaw exists in versions prior to 1.10.11 during the handling of DTLS-SRTP media setup, specifically in the DTLS handshake's ClientHello phase. An attacker can exploit a race condition by sending a ClientHello message containing an invalid CipherSuite (e.g., TLS_NULL_WITH_NULL_NULL) to the FreeSWITCH server's media port. This malformed message triggers a DTLS error, causing the media session to be torn down, which cascades to tearing down the signaling session (SIP). Because the attack can be repeated continuously, it results in a Denial of Service (DoS) by preventing new DTLS-SRTP encrypted calls from being established. The root cause is improper handling of exceptional conditions (CWE-703) in the DTLS handshake logic. The vulnerability does not affect confidentiality or integrity but severely impacts availability. The fix introduced in FreeSWITCH 1.10.11 involves dropping packets from IP addresses that have not passed ICE (Interactive Connectivity Establishment) validation, effectively blocking malicious handshake attempts from unauthorized sources. No known exploits are reported in the wild yet, but the vulnerability is remotely exploitable without authentication or user interaction, making it a significant risk for telecom environments relying on FreeSWITCH for secure media transport.

CWE-703Improper Check or Handling of Exceptional Conditions (opens in a new tab)
Pillar weaknessOWASP Top 10 A10:2025: Mishandling of Exceptional Conditions (opens in a new tab)
The product does not properly anticipate or handle exceptional conditions that rarely occur during normal operation of the product.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
OWASP Cheat Sheets
Logging (opens in a new tab)
Error Handling (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Nov 2025, 19:26 UTC

WeaknessesCWE-703

Technical details

References

Community reviews

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