{"id":"CVE-2026-49840","summary":"FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing","details":"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.","aliases":["GHSA-g597-9fgg-ghg9"],"modified":"2026-07-08T08:12:25.974299Z","published":"2026-06-09T16:00:56.687Z","database_specific":{"cwe_ids":["CWE-122","CWE-195","CWE-20","CWE-787"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49840.json","cna_assigner":"GitHub_M"},"references":[{"type":"WEB","url":"https://github.com/signalwire/freeswitch/releases/tag/v1.11.1"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49840.json"},{"type":"ADVISORY","url":"https://github.com/signalwire/freeswitch/security/advisories/GHSA-g597-9fgg-ghg9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49840"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/signalwire/freeswitch","events":[{"introduced":"0"},{"fixed":"c2c59645f6911a76589e5008c4d73349ded44b65"}],"database_specific":{"cpe":"cpe:2.3:a:freeswitch:freeswitch:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"1.11.1"}],"source":["AFFECTED_FIELD","CPE_RANGE","REFERENCES"]}}],"versions":["v1.11.0","v1.10.12","v1.10.11","v1.10.10","v1.10.9","v1.10.8","v1.10.7","v1.10.6","v1.10.5","v1.10.4","v1.10.3","v1.10.2","v1.10.1","v1.10.0","v1.6.0","v1.5.final","v1.5.14","v1.5.13","v1.5.12","v1.5.10","v.15.9","v1.5.8","v1.5.5","v1.5.2","v1.5.1","v1.5.0","v1.3.17-final","v1.3.16","v1.3.15","v1.3.14","v1.3.13","v1.3.12","v.1.3.12","v0.0.1","v1.3.11","v1.3.10","v1.3.9","v1.3.8","v1.3.7","v1.3.6","v1.3.5","v1.3.4","v1.3.3","v1.3.2","v1.3.1","v1.3.0","v1.2-rc2","v1.2-rc1","git2svn-syncpoint-master"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-49840.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H"}]}