CVE-2026-49840
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.
Scoring
- Severity
- CRITICAL
- CVSS base score
- 9.1
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
- EPSS probability
- 0.31%
- CWE
- CWE-20, CWE-122, CWE-195, CWE-787
- Published
- 2026-06-09
- Last modified
- 2026-06-09
Affected products
- signalwire freeswitch
Weakness type
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