CVE-2026-81097
HighCVSS 8.4Exploitation Probability (EPSS)
Low risk7th percentile - higher than 7% of all known CVEs
Summary
The execute_ruby tool is documented as a read-only Ruby sandbox, but its denylist does not cover the spawn entry points of the pseudo-terminal library. A normal tool call could start a shell and execute commands as the server account. Version 1.6.1 restricts allowed requires and blocks dynamic dispatch, and 2.0.0 removes the tool.
Risk Assessment
Arbitrary command execution on the server may lead to full system compromise and data integrity violation.
Recommendation
Upgrade to version 1.6.1 or later, preferably 2.0.0, which removes the tool.
Original NVD description (English source)
The execute_ruby tool is documented as a read-only Ruby sandbox and is enforced by a pattern denylist together with replacements for the process-spawning methods on Kernel. The pseudo-terminal library's spawn entry points are neither in the denylist nor replaced, so a normal tool call could reach them and start a shell, executing commands as the account running the server and outside the guarded methods. The denylist was introduced with the tool in 1.4.0 and never covered those entry points through 1.6.0. Version 1.6.1 restricts the requires the sandbox permits to a data-only list and blocks dynamic dispatch to execution entry points; 2.0.0 removes the tool.