High severity · published Jun 9, 2026
CVE-2026-49847
FreeSWITCH: Stack overflow in bundled cJSON parser via deeply nested JSON
7.5
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 36% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FR
freeswitch · signalwire
< 1.11.1 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-49847
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-49847
Release Notes
https://github.com/signalwire/freeswitch/releases/tag/v1.11.1
Third Party Advisory
https://github.com/signalwire/freeswitch/security/advisories/GHSA-2v74-pcgh-75wg
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