CVE-2026-85661 excel-mcp-server 0.1.8 Arbitrary File Read/Write via stdio mode
Attackers can read and write arbitrary files by supplying unchecked paths when the server runs in stdio mode without a configured file path.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-85661?
CVE-2026-85661 is a critical path traversal vulnerability in haris-musa excel-mcp-server, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
excel-mcp-server 0.1.8 fails to enforce path confinement in stdio mode when EXCEL_FILES_PATH is unset, allowing attackers to read and write arbitrary files. Attackers can supply unchecked file paths to read and write tools to access any file accessible to the process.
Weakness: CWE-22
Which versions are affected by CVE-2026-85661?
How do I fix CVE-2026-85661?
No fix has been published for CVE-2026-85661 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-85661 being exploited?
There is no known exploitation of CVE-2026-85661 in the wild and no public exploit code.
Sources
Also known as GHSA-xv88-r947-5c3v.