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

Quick assessment

Affected
signalwire freeswitch
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

FreeSWITCH是美国Anthony Minessale个人开发者的研发的一套免费、开源的通信软件。该软件可用于创建音、视频以及短消息类产品和应用。 FreeSWITCH 1.11.1之前版本存在资源管理错误漏洞，该漏洞源于mod_verto的WebSocket帧循环在任何身份验证检查之前拦截以#为前缀的速度测试协议，使用atoi解析#SPU中声明的有效载荷大小，仅拒绝非正值，因此未经身份验证的对等端可以请求最多INT_MAX字节，服务器在下载阶段回写大约size乘以10字节的数据，每个请求约20 G

CVSS 7.5 · High EPSS 0.58% · P46

Affected Version Matrix 1

VendorProduct Version RangeStatus
signalwire freeswitch < 1.11.1 affected
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I. Basic Information for CVE-2026-49842

Vulnerability Information
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Vulnerability Title
FreeSWITCH: Pre-authentication bandwidth amplification via `mod_verto` speed-test frames
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Vulnerability Title
FreeSWITCH 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
FreeSWITCH是美国Anthony Minessale个人开发者的研发的一套免费、开源的通信软件。该软件可用于创建音、视频以及短消息类产品和应用。 FreeSWITCH 1.11.1之前版本存在资源管理错误漏洞，该漏洞源于mod_verto的WebSocket帧循环在任何身份验证检查之前拦截以#为前缀的速度测试协议，使用atoi解析#SPU中声明的有效载荷大小，仅拒绝非正值，因此未经身份验证的对等端可以请求最多INT_MAX字节，服务器在下载阶段回写大约size乘以10字节的数据，每个请求约20 G
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
signalwire freeswitch < 1.11.1 -

II. Public POCs for CVE-2026-49842

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 7803 chars
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III. Intelligence Information for CVE-2026-49842

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Patches & Fixes for CVE-2026-49842 (1)

Vendor Advisories for CVE-2026-49842 (1)

Same Patch Batch · signalwire · 2026-06-09 · 9 CVEs total

CVE-2026-49841 9.8 CRITICAL FreeSWITCH: Pre-authentication heap buffer overflow in `mod_verto` HTTP POST body read
CVE-2026-49840 9.1 CRITICAL FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing
CVE-2026-45771 7.5 HIGH Freeswitch Denial-of-Service in SIP PUBLISH Requests via XML Entity Expansion
CVE-2026-49847 7.5 HIGH FreeSWITCH: Stack overflow in bundled cJSON parser via deeply nested JSON
CVE-2026-49475 7.5 HIGH FreeSWITCH: Out-of-bounds memory access in core STUN attribute parsing
CVE-2026-49843 5.3 MEDIUM FreeSWITCH: Pre-authentication session eviction via attacker-chosen `sessid` in `mod_verto
CVE-2026-49472 5.3 MEDIUM FreeSWITCH includes a vulnerable function, PREFIX(prologTok)() from libexpat
CVE-2026-49848 4.3 MEDIUM FreeSWITCH: Pre-authentication `userVariables` injection in `mod_verto`

IV. Related Vulnerabilities

Same product: freeswitch
Same vendor: signalwire
Same weakness: CWE-400

V. Comments for CVE-2026-49842

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