CVE-2026-49841: FreeSWITCH: Pre-authentication heap buffer overflow in `mod_verto` HTTP POST body read

Vulnerability summary

CVE-2026-49841 is a critical (CVSS 9.8) Heap-based Buffer Overflow vulnerability in freeswitch. EPSS estimates a 0.39% chance of exploitation in the next 30 days, higher than 33.9% of scored vulnerabilities.

Timeline

1. 09-06-2026
   PublishedVulnerability first disclosed.
2. 11-06-2026
   Last modifiedVulnerability information updated.

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, the mod_verto HTTP request handler allocates a fixed 2 MiB buffer for a POST application/x-www-form-urlencoded body but accepts Content-Length up to just under 10 MiB. The body-read loop is bounded by Content-Length rather than the buffer size, producing an attacker-controlled heap overflow of up to ~8 MiB -- before the HTTP basic-auth check runs. This issue has been patched in version 1.11.1.

• CWE-122Heap-based Buffer OverflowThe product writes past the end of a buffer that was allocated on the heap.
• CWE-131Incorrect Calculation of Buffer SizeThe product does not correctly calculate the size to be used when allocating a buffer.