{"document":{"category":"csaf_vex","csaf_version":"2.0","title":"CVE-2026-49840: FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing","publisher":{"category":"vendor","name":"HarborGuard Database","namespace":"https://database.harborguard.co"},"tracking":{"id":"CVE-2026-49840","status":"final","version":"1","initial_release_date":"2026-06-09T16:00:56.687Z","current_release_date":"2026-06-09T17:00:21.313Z","revision_history":[{"date":"2026-06-09T16:00:56.687Z","number":"1","summary":"Initial machine-readable export from HarborGuard."}]},"distribution":{"tlp":{"label":"WHITE"},"text":"Public CVE data; freely redistributable."},"notes":[{"category":"description","text":"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":"CVE description"}],"references":[{"category":"self","summary":"CVE-2026-49840 on HarborGuard Database","url":"https://database.harborguard.co/cve/CVE-2026-49840"},{"category":"external","summary":"CVE Record","url":"https://www.cve.org/CVERecord?id=CVE-2026-49840"},{"category":"external","summary":"https://github.com/signalwire/freeswitch/security/advisories/GHSA-g597-9fgg-ghg9","url":"https://github.com/signalwire/freeswitch/security/advisories/GHSA-g597-9fgg-ghg9"},{"category":"external","summary":"https://github.com/signalwire/freeswitch/releases/tag/v1.11.1","url":"https://github.com/signalwire/freeswitch/releases/tag/v1.11.1"}]},"product_tree":{"branches":[{"category":"vendor","name":"signalwire","branches":[{"category":"product_name","name":"freeswitch","branches":[{"category":"product_version","name":"< 1.11.1","product":{"name":"signalwire freeswitch < 1.11.1","product_id":"CSAFPID-1","product_identification_helper":{"cpe":"cpe:2.3:a:signalwire:freeswitch:\\<_1.11.1:*:*:*:*:*:*:*"}}}]}]}]},"vulnerabilities":[{"cve":"CVE-2026-49840","title":"FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing","notes":[{"category":"description","text":"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":"CVE description"}],"product_status":{"known_affected":["CSAFPID-1"]},"scores":[{"cvss_v3":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H","baseScore":9.1,"baseSeverity":"CRITICAL"},"products":["CSAFPID-1"]}],"remediations":[{"category":"none_available","details":"No fixed version is published yet. Monitor the upstream advisory.","product_ids":["CSAFPID-1"]}]}]}