Vulnerability 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, esl_recv_event() parses Content-Length with atol() and passes the result straight to malloc(len + 1) with no sign or magnitude check. A malicious or man-in-the-middle ESL peer can send a frame with a negative Content-Length to corrupt the heap of, or crash, any process linked against libesl, before the client has authenticated to that peer. This issue has been patched in version 1.11.1.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Freeswitch | Freeswitch | < 1.11.1 |
Related Weaknesses (CWE)
References
- https://github.com/signalwire/freeswitch/releases/tag/v1.11.1Release Notes
- https://github.com/signalwire/freeswitch/security/advisories/GHSA-g597-9fgg-ghg9Third Party Advisory
FAQ
What is CVE-2026-49840?
CVE-2026-49840 is a vulnerability with a CVSS score of 9.1 (CRITICAL). 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 ...
How severe is CVE-2026-49840?
CVE-2026-49840 has been rated CRITICAL with a CVSS base score of 9.1/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-49840?
Check the references section above for vendor advisories and patch information. Affected products include: Freeswitch Freeswitch.