{"id":"CVE-2026-49840","aliases":["EUVD-2026-35471","GHSA-g597-9fgg-ghg9"],"status":"published","title":"FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing","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.","severity":{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.0031,"percentile":0.24126,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-122","CWE-195","CWE-20","CWE-787"],"published":"2026-06-09T16:00:56Z","modified":"2026-10-28T02:30:36Z","products":[{"vendor":"freeswitch","product":"freeswitch"},{"vendor":"signalwire","product":"freeswitch"}],"references":[{"url":"https://github.com/signalwire/freeswitch/security/advisories/GHSA-g597-9fgg-ghg9","tags":["x_refsource_CONFIRM","Third Party Advisory","advisory"]},{"url":"https://github.com/signalwire/freeswitch/releases/tag/v1.11.1","tags":["x_refsource_MISC","Release Notes","web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49840.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49840","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-49840","title":"FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing","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.","status":"published","published":"2026-06-09T16:00:56.687Z","modified":"2026-06-09T17:00:21.313Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"critical","assessor":"cna"}],"cwes":["CWE-20","CWE-122","CWE-195","CWE-787"],"updated_at":"2026-11-02T13:34:59.78118Z"}],"euvd":[{"id":"EUVD-2026-35471","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.","status":"published","published":"2026-06-09T16:00:56Z","modified":"2026-06-09T17:00:21Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T18:20:47.241018Z"}],"nvd":[{"id":"CVE-2026-49840","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.","status":"published","published":"2026-06-09T17:17:47.703Z","modified":"2026-07-23T08:10:00.137Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"critical","assessor":"secondary"}],"cwes":["CWE-20","CWE-122","CWE-195","CWE-787"],"updated_at":"2026-11-02T14:12:23.109705Z"}],"osv":[{"id":"CVE-2026-49840","title":"FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing","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.","status":"published","published":"2026-06-09T16:00:56.687Z","modified":"2026-10-28T02:30:36.572385242Z","cvss":[{"version":"3.1","score":9.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","level":"critical"}],"cwes":["CWE-122","CWE-195","CWE-20","CWE-787"],"updated_at":"2026-11-02T15:45:07.060148Z"}]}}