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CVE-2026-49847 signalwire CVE debrief

CVE-2026-49847 is a HIGH severity vulnerability in FreeSWITCH, a Software Defined Telecom Stack. A single unauthenticated WebSocket frame with a deeply nested JSON document can crash 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.

Vendor
signalwire
Product
freeswitch
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-09
Original CVE updated
2026-06-10
Advisory published
2026-06-09
Advisory updated
2026-06-10

Who should care

Users of FreeSWITCH software-defined telecom stack, particularly those using versions prior to 1.11.1, should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability is caused by a stack overflow in the FreeSWITCH process when handling a deeply nested JSON document in a WebSocket frame. This can be exploited by an unauthenticated attacker, leading to a denial of service (DoS) condition.

Defensive priority

HIGH

Recommended defensive actions

  • Upgrade to FreeSWITCH version 1.11.1 or later.
  • Implement additional security measures to restrict access to the WebSocket interface.

Evidence notes

The vulnerability is documented in the official CVE record [cve-org] and the NVD detail page [nvd].

Official resources

CVE-2026-49847 was published on 2026-06-09T17:17:48.320Z and modified on 2026-06-10T15:06:45.590Z.