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

High 7.5 Published 9 Jun 2026 Updated 9 Jun 2026

An unauthenticated attacker can crash the FreeSWITCH process by sending a deeply nested JSON document, terminating all active calls and sessions.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-49847?

CVE-2026-49847 is a high-severity denial of service vulnerability in signalwire freeswitch, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-674

Which versions are affected by CVE-2026-49847?

It affects 1 product.

Products include Freeswitch Freeswitch.

How do I fix CVE-2026-49847?

No fix has been published for CVE-2026-49847 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-49847 being exploited?

There is no known exploitation of CVE-2026-49847 in the wild and no public exploit code.

Sources

Also known as GHSA-2v74-pcgh-75wg.