CVE-2026-49842 FreeSWITCH: Pre-authentication bandwidth amplification via `mod_verto` speed-test frames
Unauthenticated attackers can cause severe bandwidth amplification and resource exhaustion in FreeSWITCH via mod_verto speed-test frames.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-49842?
CVE-2026-49842 is a high-severity denial of service vulnerability in signalwire freeswitch, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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 1.11.1, mod_verto's WebSocket frame loop intercepts a #-prefixed speed-test protocol (#SPU / #SPB / #SPE) before any authentication check. The declared payload size in #SPU was parsed with atoi() and only rejected non-positive values, so an unauthenticated peer could request up to INT_MAX bytes. The server then wrote roughly size * 10 bytes back during the download phase, on the order of 20 GB per request, yielding strong outbound bandwidth amplification from a short request. This issue has been patched in version 1.11.1.
Weakness: CWE-400
Which versions are affected by CVE-2026-49842?
It affects 1 product.
Products include Freeswitch Freeswitch.
How do I fix CVE-2026-49842?
No fix has been published for CVE-2026-49842 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-49842 being exploited?
There is no known exploitation of CVE-2026-49842 in the wild and no public exploit code.
Other vulnerabilities in signalwire freeswitch
- CVE-2026-49841 FreeSWITCH: Pre-authentication heap buffer overflow in `mod_verto` HTTP POST body read
- CVE-2019-19492 Hardcoded credentials in n/a
- CVE-2026-49840 FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing
- CVE-2021-41145 FreeSWITCH susceptible to Denial of Service via SIP flooding
- CVE-2026-45771 Freeswitch Denial-of-Service in SIP PUBLISH Requests via XML Entity Expansion
Sources
Also known as GHSA-p3gx-p2w7-wp35.