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

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-09 · updated 2026-07-23
Weakness: CWE-674

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.

Affected products

signalwire freeswitch: before 1.11.1 — fixed in 1.11.1

How to fix

Upgrade to a fixed version: signalwire freeswitch 1.11.1. Check the vendor advisory for mitigations.

References

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