CVE-2026-55581
Command injection via /bin/bash -c bypass allows arbitrary command execution as mcpuser.
Is CVE-2026-55581 being exploited?
Not confirmed. CVE-2026-55581 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.34% probability of exploitation in the next 30 days.
How severe is CVE-2026-55581?
CVE-2026-55581 is rated High with a CVSS score of 8.4. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-55581?
Yes. A fix has been recorded for CVE-2026-55581. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-55581 affect?
CVE-2026-55581 affects mcp-shell < 0.6.0, mcp-shell Docker deployments using default security.yaml, shell_exec MCP tool. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-55581?
Upgrade to mcp-shell 0.6.0; remove /bin/bash from allowed_executables and audit deployments.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Arbitrary command execution as mcpuser via shell_exec by supplying '/bin/bash -c <cmd>', bypassing allowlist checks.
Immediate action required
- affected< 0.6.0
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.