# CVE-2026-109427: Telegram-Stremio 5.1.0 Broken Object Authorization via Stream IDs

> Authenticated users can access private Telegram messages and thumbnails by forging stream IDs, bypassing authorization checks in the Telegram-Stremio addon.

- **Severity:** High 7.1 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Oct 2026
- **Updated:** 26 Oct 2026
- **Also known as:** GHSA-q45w-888c-vpfr

## What is CVE-2026-109427?

CVE-2026-109427 is a high-severity missing authorization vulnerability in weebzone Telegram-Stremio, published on 12 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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.

Weakness: CWE-862 (Missing Authorization), CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-109427?


## How do I fix CVE-2026-109427?

No fix has been published for CVE-2026-109427 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-109427 being exploited?

There is no known exploitation of CVE-2026-109427 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-109427 and fix it if it is affected.

What it is: CVE-2026-109427 is a high-severity missing authorization vulnerability in weebzone Telegram-Stremio, published on 12 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-109427 in the wild and no public exploit code.

Affected product: weebzone Telegram-Stremio. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-109427/ (Markdown: https://insights.sbomify.com/CVE-2026-109427/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-109427
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-109427
- OSV: https://osv.dev/vulnerability/CVE-2026-109427

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-109427/
Summaries are generated and may contain mistakes; the official description above is the record.