# 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.

- **Severity:** High 8.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Jun 2026
- **Updated:** 22 Jun 2026
- **Also known as:** GHSA-4hf8-5mjm-rfgq

## 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.

Weakness: CWE-862 (Missing Authorization), CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-49357?

2 open source packages ship an affected version, including line-desktop-mcp.


| Package | Ecosystem | 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.

## Is CVE-2026-49357 being exploited?

There is no known exploitation of CVE-2026-49357 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-49357 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-49357 in the wild and no public exploit code.

Affected packages and fixed versions:
- line-desktop-mcp (npm): affected all versions; fixed in 1.1.2
- line-desktop-mcp (npm): affected all versions; fixed in 1.1.2

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-2026-49357/ (Markdown: https://insights.sbomify.com/CVE-2026-49357/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49357
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49357
- OSV: https://osv.dev/vulnerability/CVE-2026-49357

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-49357/
Summaries are generated and may contain mistakes; the official description above is the record.