FreeSWITCH: Pre-authentication process termination in the Event Socket via an unbounded Content-Length
Affects FreeSWITCH 1.11.1 and earlier, where the Event Socket listener admits hosts beyond the loopback default via apply-inbound-acl. Fixed in 1.11.2.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 1.11.2
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Affected versions are FreeSWITCH 1.11.1 and earlier (fixed in 1.11.2); the affected module is mod_event_socket. The Event Socket listener must be reachable by the attacker from an address admitted by apply-inbound-acl; default install with no ACL limits access to the local host. The outbound socket dialplan application is also affected when FreeSWITCH connects to a hostile application server.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 23/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: yes
- Technical impact: partial
Summary
FreeSWITCH's mod_event_socket module can be crashed by an unauthenticated Content-Length value, which terminates the whole process and drops all active calls until the service is restarted. An attacker can reach it remotely, without logging in, by sending a single packet from any host the inbound ACL admits, and the outbound socket dialplan path is also affected when FreeSWITCH connects to a hostile application server.
Read the original 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 1.11.2, mod_event_socket used an unauthenticated Content-Length value directly as the allocation size for an Event Socket message body. Negative or extremely large values could overflow the terminator calculation or force an allocation failure through a helper that aborts the FreeSWITCH process. The header is parsed before the Event Socket password, so any host admitted by apply-inbound-acl can trigger termination with its first packet; the default loopback ACL limits ordinary installations to local clients. The outbound socket dialplan path is also affected when FreeSWITCH connects to a hostile application server, and process termination drops every active call until the service is restarted. This issue is fixed in version 1.11.2.
cve.now Index
- Exploitation0/40No signal
- Exposure15/25Specific setups only, CISA rates it automatable
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.5/10CVSS 7.5
- No patch0/5No signal
What would change the score
- Would score about 73 if added to CISA KEV
- Would score about 68 if CISA's SSVC rates exploitation active
What to do
Check whether your setup matches what the bug needs.
Affected versions are FreeSWITCH 1.11.1 and earlier (fixed in 1.11.2); the affected module is mod_event_socket. The Event Socket listener must be reachable by the attacker from an address admitted by apply-inbound-acl; default install with no ACL limits access to the local host. The outbound socket dialplan application is also affected when FreeSWITCH connects to a hostile application server.Upgrade to a fixed version: 1.11.2.
Workaround: Leave apply-inbound-acl unset, or set it to loopback.auto or an explicit list of trusted hosts, so the listener closes disallowed connections before parsing anything.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: partial
- Record last updated
Affected versions
- signalwire freeswitch
fixed in 1.11.2
Evidence 3
- Advisory
- Repository
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-116787
Is CVE-2026-116787 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A single crafted packet with an unbounded Content-Length, sent before authentication, terminates the FreeSWITCH process. Every call in progress drops, and the daemon does not recover on its own until it is restarted.Source: github.com
Which versions are affected by CVE-2026-116787?
freeswitch: before 1.11.2.Source: cve.now feed data
Am I affected, and how do I check?
Versions 1.11.1 and earlier are affected, through the mod_event_socket module. The Event Socket listener must be reachable from an address admitted by apply-inbound-acl; a default install with no ACL limits access to the local host. The outbound socket dialplan application is also affected when FreeSWITCH connects to a hostile application server. To check, look at your FreeSWITCH version and at the apply-inbound-acl setting for the Event Socket.Source: github.com
How do I fix CVE-2026-116787?
Upgrade to FreeSWITCH 1.11.2 or later, which contains the fix.Source: github.com