{"id":"CVE-2026-109427","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-109427","generatedAt":"2026-10-28T06:35:47.249Z","title":"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…","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.","published":"2026-10-12T21:17:11.000Z","lastModified":"2026-10-26T21:17:29.000Z","status":"Deferred","sourceIdentifier":"disclosure@vulncheck.com","cvss":{"version":"4.0","score":7.1,"severity":"HIGH","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-639","CWE-862"],"affected":[],"epss":{"score":0.00209,"percentile":0.10896,"date":"2026-10-27","history":[{"date":"2026-10-13","score":0.00209,"percentile":0.10204}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.21%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-12T21:17:11.000Z","detail":{"score":"7.1","severity":"HIGH","publishedAt":"2026-10-12T21:17:11.460Z"},"summary":"New CVE, high severity (CVSS 7.1)."}],"references":[{"url":"https://gist.github.com/mansurmavlankulov/489554cad7b38e07b9651c217f00fffb","source":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/telegram-stremio-broken-object-authorization-via-stream-ids","source":"disclosure@vulncheck.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-109427","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}