{"cve":"CVE-2026-55581","nvd":{"published":"2026-08-25T16:16:55.470","modified":"2026-09-09T21:07:31.353","status":"Deferred","description":"mcp-shell is an MCP server for running shell commands securely, auditably, and on demand. Prior to 0.6.0, the default Docker security.yaml includes /bin/bash in allowed_executables, while security.go validates only the first token and checkBlockedPatternsAndCommands does not reject the shell command-mode flag -c. A caller of the shell_exec MCP tool can provide the command argument `/bin/bash -c <arbitrary-command>`, which passes validation and reaches executor.go, where parseCommand and exec.CommandContext execute the arbitrary command as mcpuser outside the intended allowlist. This issue is fixed in version 0.6.0.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.4},"cwes":["CWE-78","CWE-183","CWE-1188"],"references":["https://github.com/sonirico/mcp-shell/commit/f31377fce6ec31114e5a4398c0e5270552bce09f","https://github.com/sonirico/mcp-shell/pull/16","https://github.com/sonirico/mcp-shell/releases/tag/v0.6.0","https://github.com/sonirico/mcp-shell/security/advisories/GHSA-3x77-wg38-92r3","https://github.com/sonirico/mcp-shell/security/advisories/GHSA-3x77-wg38-92r3"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:50:17.453294893+00:00"},"epss":{"cve":"CVE-2026-55581","score":0.00454,"percentile":0.3944,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-3x77-wg38-92r3","url":"https://osv.dev/vulnerability/GHSA-3x77-wg38-92r3","summary":"mcp-shell has a Secure Mode Allowlist Bypass via Default `/bin/bash` Executable","modified":"2026-09-09T05:15:05.808816109Z","packages":[{"ecosystem":"Go","name":"github.com/sonirico/mcp-shell","purl":"pkg:golang/github.com/sonirico/mcp-shell","ranges":["<0.6.0"],"fixed":["0.6.0"]}]},{"id":"GO-2026-6290","url":"https://osv.dev/vulnerability/GO-2026-6290","summary":"mcp-shell has a Secure Mode Allowlist Bypass via Default `/bin/bash` Executable in github.com/sonirico/mcp-shell","modified":"2026-08-26T15:15:13.381046660Z","packages":[{"ecosystem":"Go","name":"github.com/sonirico/mcp-shell","purl":"pkg:golang/github.com/sonirico/mcp-shell","ranges":["<0.6.0"],"fixed":["0.6.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}