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.
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Tue, 09 Jun 2026 17:30:00 +0000
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Tue, 09 Jun 2026 16:30:00 +0000
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| 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. | |
| Title | FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing | |
| Weaknesses | CWE-122 CWE-195 CWE-20 CWE-787 |
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cvssV3_1
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Status: PUBLISHED
Assigner: GitHub_M
Published: 2026-06-09T16:00:56.687Z
Updated: 2026-06-09T17:00:21.313Z
Reserved: 2026-06-01T18:50:36.056Z
Link: CVE-2026-49840
Updated: 2026-06-09T17:00:09.680Z
Status : Received
Published: 2026-06-09T17:17:47.703
Modified: 2026-06-09T17:17:47.703
Link: CVE-2026-49840
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