CVE-2026-49847: FreeSWITCH: Stack overflow in bundled cJSON parser via deeply nested JSON
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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
FreeSWITCHto a version that resolves this vulnerability.Fixed in 1.11.1
Event History
Frequently Asked Questions
What is the severity of CVE-2026-49847?
The severity of CVE-2026-49847 is rated as high with a score of 7.5.
How do I fix CVE-2026-49847?
To fix CVE-2026-49847, upgrade FreeSWITCH to version 1.11.1 or later.
What causes the vulnerability in CVE-2026-49847?
CVE-2026-49847 is caused by a stack overflow in the cJSON parser when processing deeply nested JSON documents.
Which versions of FreeSWITCH are affected by CVE-2026-49847?
Versions of FreeSWITCH prior to 1.11.1 are affected by CVE-2026-49847.
Can CVE-2026-49847 be exploited remotely?
Yes, CVE-2026-49847 can be exploited remotely through a malicious WebSocket frame.