FreeSWITCH: Out-of-bounds read in mod_rtmp H.264 video message parsing
Only deployments that build and load mod_rtmp are exposed, covering all 1.10.x and 1.11.x releases and current master. 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. Deployment builds and loads mod_rtmp. Affected versions are all released 1.10.x and 1.11.x versions, and current master. An RTMP call session carrying video must be placed by the client, and the affected code runs on the video messages that follow.
- 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_rtmp module has an out-of-bounds read flaw in H.264 video message parsing that a remote attacker can trigger over the network without logging in, crashing the process and ending FreeSWITCH and all active calls. It affects only deployments that build and load mod_rtmp and accept video calls, commonly on TCP port 1935.
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, rtmp_rtmp2rtpH264() trusted the length prefix of each inbound H.264 NAL unit without checking it against the bytes remaining in the RTMP message. An oversized declared unit underflowed the unsigned remaining-byte counter and advanced the parser beyond its receive buffer, where the next length-prefix read could crash the process. The flaw affects deployments that build and load mod_rtmp and accept video call sessions, commonly on TCP port 1935; placing the call requires a directory login where auth-calls is true, while no credentials are required where auth-calls is absent or false. A remote client can terminate FreeSWITCH and every active call, but the defect supplies no write primitive and memory disclosure has not been demonstrated. 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.
Deployment builds and loads mod_rtmp. Affected versions are all released 1.10.x and 1.11.x versions, and current master. An RTMP call session carrying video must be placed by the client, and the affected code runs on the video messages that follow.Upgrade to a fixed version: 1.11.2.
Workaround: Leave mod_rtmp unloaded unless RTMP client support is required.
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-2026-116568
Is CVE-2026-116568 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?
The bug is an out-of-bounds read in how FreeSWITCH parses H.264 video messages in its RTMP module. A remote client sending crafted video messages can crash the FreeSWITCH process, which ends every call the instance is handling. The defect is a read-only flaw, and disclosure of memory to another party has not been demonstrated.Source: github.com, github.com
Which versions are affected by CVE-2026-116568?
freeswitch: before 1.11.2.Source: cve.now feed data
Am I affected, and how do I check?
All released 1.10.x and 1.11.x versions and current master are affected, but only when mod_rtmp is built and loaded. The exposed path needs an RTMP call session carrying video, which the client requests when placing the call. Check whether mod_rtmp is loaded in the FreeSWITCH module configuration to see if this setup applies.Source: github.com, github.com
How do I fix CVE-2026-116568?
Upgrade to FreeSWITCH 1.11.2, which the vendor strongly encourages as soon as possible. If RTMP client support is not required, leave mod_rtmp unloaded as a workaround.Source: github.com, github.com