{"id":"CVE-2026-109427","published":"2026-10-12T21:17:11.460","lastModified":"2026-10-16T19:18:44.867","description":"Telegram-Stremio through 5.1.0 contains a broken object-level authorization vulnerability that allows authenticated token holders to access arbitrary chat messages by forging unsigned, unauthenticated stream IDs decoded via encode_string/decode_string functions. Attackers can craft or enumerate sequential msg_id values and set a global flag in the stream_handler endpoint to route requests through the operator's personal Userbot account, exposing private channels, groups, and Saved Messages, while the unauthenticated thumb_handler endpoint further discloses thumbnails from those same chats without any token validation.","cvssScore":6.5,"cvssSeverity":"MEDIUM","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","cwes":["CWE-639","CWE-862"],"vendors":[],"products":[],"references":[{"url":"https://gist.github.com/mansurmavlankulov/489554cad7b38e07b9651c217f00fffb","tags":[]},{"url":"https://www.vulncheck.com/advisories/telegram-stremio-broken-object-authorization-via-stream-ids","tags":[]}],"exploitRefs":[{"url":"https://gist.github.com/mansurmavlankulov/489554cad7b38e07b9651c217f00fffb","tags":[]}],"hasPoc":true,"ai":null}