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.

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History

Mon, 12 Oct 2026 20:45:00 +0000

Type Values Removed Values Added
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.
Title Telegram-Stremio 5.1.0 Broken Object Authorization via Stream IDs
Weaknesses CWE-639
CWE-862
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N'}

cvssV4_0

{'score': 7.1, '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'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-10-12T20:35:49.858Z

Reserved: 2026-10-12T15:52:36.681Z

Link: CVE-2026-109427

cve-icon Vulnrichment

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cve-icon NVD

Status : Received

Published: 2026-10-12T21:17:11.460

Modified: 2026-10-12T21:17:11.460

Link: CVE-2026-109427

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses