CVE-2026-109427

Telegram-Stremio 5.1.0 Broken Object Authorization via Stream IDs

State: Published
Severity: 7.1 High
Published: Oct 12, 2026
Updated: Oct 26, 2026
Reserved: Oct 12, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	7.1 High	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	VulnCheck
3.1	6.5 Medium	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N	VulnCheck

Weaknesses

CWE-639 Authorization Bypass Through User-Controlled Key
CWE-862 Missing Authorization

Affected Products

Product	Versions
Telegram-Stremioweebzone	5.1.0 and earlierAffected

References

Researcher Disclosuretechnical-description
VulnCheck Advisory: Telegram-Stremio 5.1.0 Broken Object Authorization via Stream IDsthird-party-advisory

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