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CVE-2026-49843— FreeSWITCH: Pre-authentication session eviction via attacker-chosen `sessid` in `mod_verto`

Quick assessment

Affected
signalwire freeswitch
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
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之前版本存在授权问题漏洞，该漏洞源于mod_verto的JSON-RPC处理程序在身份验证门之前将连接绑定到客户端提供的sessid，绑定将连接插入全局会话哈希，并在键冲突时丢弃该槽位的先前占用者，向其发送verto.punt、分离其呼叫并关闭其套接字，知道目标会话UUID的未经身份验证的网络攻击者因此可以驱逐合法客户端

CVSS 5.3 · Medium EPSS 0.50% · P41

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
signalwire freeswitch < 1.11.1 affected
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I. Basic Information for CVE-2026-49843

Vulnerability Information
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Vulnerability Title
FreeSWITCH: Pre-authentication session eviction via attacker-chosen `sessid` in `mod_verto`
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 JSON-RPC handler bound the connection to the client-supplied sessid on the first frame, before the authentication gate. Binding inserts the connection into the global session hash and, on a key collision, drops the prior occupant of that slot — sending it a verto.punt, detaching its calls, and closing its socket. An unauthenticated network attacker who knows a target session UUID could therefore evict the legitimate client. 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:L
Source: CVE Program / CVE List V5
Vulnerability Type
认证机制不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
FreeSWITCH 授权问题漏洞
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之前版本存在授权问题漏洞，该漏洞源于mod_verto的JSON-RPC处理程序在身份验证门之前将连接绑定到客户端提供的sessid，绑定将连接插入全局会话哈希，并在键冲突时丢弃该槽位的先前占用者，向其发送verto.punt、分离其呼叫并关闭其套接字，知道目标会话UUID的未经身份验证的网络攻击者因此可以驱逐合法客户端
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-2026-49843

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III. Intelligence Information for CVE-2026-49843

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Patches & Fixes for CVE-2026-49843 (1)

Vendor Advisories for CVE-2026-49843 (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-2026-49842 7.5 HIGH FreeSWITCH: Pre-authentication bandwidth amplification via `mod_verto` speed-test frames
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-2026-49472 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-287

V. Comments for CVE-2026-49843

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