# CVE-2026-49840

## Summary

- **CVE ID:** CVE-2026-49840
- **Severity:** CRITICAL
- **CVSS Score:** 9.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H)
- **CWE:** CWE-20, CWE-122, CWE-195, CWE-787
- **Published:** Jun 9, 2026
- **Last Modified:** Jun 9, 2026

## 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.

## Affected Products

- signalwire — freeswitch (< 1.11.1)

## References

- [CNA](https://github.com/signalwire/freeswitch/security/advisories/GHSA-g597-9fgg-ghg9)
- [CNA](https://github.com/signalwire/freeswitch/releases/tag/v1.11.1)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.31%
- **EPSS Percentile:** 23.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._