FreeSWITCH: Pre-authentication bandwidth amplification via `mod_verto` speed-test frames
CVE-2026-49842

7.5HIGH

Key Information:

Vendor

Signalwire

Status
Freeswitch
Vendor
CVE Published:
9 June 2026

What is CVE-2026-49842?

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.

Affected Version(s)

freeswitch < 1.11.1

References

https://github.com/signalwire/freeswitch/security/advisor...
x_refsource_CONFIRM
https://github.com/signalwire/freeswitch/releases/tag/v1....
x_refsource_MISC

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.