CVE-2026-49357 Streamable HTTP mode exposes LINE Desktop read/send tools without MCP authentication
Attackers can read chat history and send messages via LINE Desktop when using the unauthenticated Streamable HTTP mode.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-49357?
CVE-2026-49357 is a high-severity missing authorization vulnerability in dtwang line-desktop-mcp, published on 19 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Line Desktop MCP is a project that, while unaffiliated with the official line-bot-mcp-server, allows users to directly operate the LINE Desktop application on Windows or Mac via MCP. `line-desktop-mcp` supports a `--http-mode` Streamable HTTP transport for use with clients such as n8n. In this mode the server binds to `0.0.0.0` and exposes the MCP `/mcp` endpoint without an MCP-layer authentication check. Prior to version 1.1.2, any network client that can reach the port can initialize a session, list tools, and call tools that read LINE Desktop chat history or send LINE messages through the already logged-in desktop application. Version 1.1.2 fixes the issue.
Which versions are affected by CVE-2026-49357?
2 open source packages ship an affected version, including line-desktop-mcp.
| Package | Affected | Fixed in |
|---|---|---|
line-desktop-mcp npm | All versions | 1.1.2 |
line-desktop-mcp npm | All versions | 1.1.2 |
How do I fix CVE-2026-49357?
Upgrade line-desktop-mcp to 1.1.2 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-49357 being exploited?
There is no known exploitation of CVE-2026-49357 in the wild and no public exploit code.
Sources
Also known as GHSA-4hf8-5mjm-rfgq.