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CVE-2026-49847— FreeSWITCH: Stack overflow in bundled cJSON parser via deeply nested JSON

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之前版本存在安全漏洞，该漏洞源于单个未经身份验证的包含深度嵌套JSON文档的WebSocket帧通过堆栈溢出崩溃FreeSWITCH进程，终止主机上的所有呼叫和会话，递归将工作线程的堆栈指针驱动到堆栈保护页，在产生任何可用写入原语之前从内核引发SIGSEGV。

CVSS 7.5 · High EPSS 0.53% · P43

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-2026-49847

Vulnerability Information
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Vulnerability Title
FreeSWITCH: Stack overflow in bundled cJSON parser via deeply nested JSON
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, a single unauthenticated WebSocket frame containing a deeply nested JSON document crashes the FreeSWITCH process via stack overflow, terminating all calls and sessions on the host. The recursion drives the worker thread's stack pointer into the stack guard page, raising SIGSEGV from the kernel before any usable write primitive develops. 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
未经控制的递归
Source: CVE Program / CVE List V5
Vulnerability Title
FreeSWITCH 安全漏洞
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之前版本存在安全漏洞，该漏洞源于单个未经身份验证的包含深度嵌套JSON文档的WebSocket帧通过堆栈溢出崩溃FreeSWITCH进程，终止主机上的所有呼叫和会话，递归将工作线程的堆栈指针驱动到堆栈保护页，在产生任何可用写入原语之前从内核引发SIGSEGV。
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-2026-49847

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 8299 chars
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III. Intelligence Information for CVE-2026-49847

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Patches & Fixes for CVE-2026-49847 (1)

Vendor Advisories for CVE-2026-49847 (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-2026-49475 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-674

V. Comments for CVE-2026-49847

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