CVE-2026-55580

HIGHPre-NVD 8.68.6—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 95% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
8.6EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.6Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

mcp-shell is an MCP server for running shell commands securely, auditably, and on demand. Prior to 0.6.0, config.go initializes Security.Enabled to false, and when MCP_SHELL_SEC_CONFIG_FILE is unset, main.go starts the documented bare-binary deployment without a security policy. SecurityValidator.validateCommand in security.go then short-circuits and allows every command supplied to the shell_exec MCP tool, so an LLM connected over stdio can execute unrestricted OS commands as the mcp-shell process user. The README from-source installation and MCP client configuration omit MCP_SHELL_SEC_CONFIG_FILE, making the insecure state the documented default. This issue is fixed in version 0.6.0.

CVSS v3
8.6
EG Score
8.6(medium)
EG Risk
43(Track)
EG Risk 43/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity86% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
5%
KEV
Not listed

Published

August 25, 2026

Last Modified

August 25, 2026

Advisory Details (4)

Auto-updated Aug 25, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github, github_pr.
github_release Patch Available

v0.6.0 — secure mode by default

Patch available: sonirico/mcp-shell v0.6.0

https://github.com/sonirico/mcp-shell/releases/tag/v0.6.0
github_commit Patch Available

commit f31377fce6ec (sonirico/mcp-shell)

Patch available: sonirico/mcp-shell v0.6.0 (contains commit f31377fce6ec)

https://github.com/sonirico/mcp-shell/commit/f31377fce6ec31114e5a4398c0e5270552bce09f
github_pr Patch Available

fix: secure mode by default + keep interpreters out of the allowlist

Patch available: sonirico/mcp-shell v0.6.0 (PR #16 merged 2026-06-14)

https://github.com/sonirico/mcp-shell/pull/16
github Patch Available🟡 PoC Available

mcp-shell — Security Disabled by Default in Bare-Binary Deploy Path + Shell Interpreter in Secure-Mode Allowlist · Advisory · sonirico/mcp-shell · GitHub

https://github.com/sonirico/mcp-shell/security/advisories/GHSA-f5pj-2738-996m

Vendor Advisories for CVE-2026-55580(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFixed inDependents
github.com/sonirico/mcp-shell—0.6.0—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 10× in last 7d / 10× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-30 01:22 UTCEPSS rescore
  2. 2026-08-29 00:15 UTCEG score recompute
  3. 2026-08-28 21:41 UTCEPSS rescore
  4. 2026-08-28 01:06 UTCEG score recompute
  5. 2026-08-27 14:25 UTCEPSS rescore
  6. 2026-08-26 15:41 UTCEG score recompute
  7. 2026-08-26 14:46 UTCEPSS rescore
  8. 2026-08-25 16:23 UTCEG score recompute
  9. 2026-08-25 15:50 UTCEG score recompute
  10. 2026-08-25 15:49 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-55580?
CVE-2026-55580 is a high vulnerability published on August 25, 2026. mcp-shell is an MCP server for running shell commands securely, auditably, and on demand. Prior to 0.6.0, config.go initializes Security.Enabled to false, and when MCPSHELLSECCONFIGFILE is unset, main.go starts the documented bare-binary deployment without a security policy.…
When was CVE-2026-55580 disclosed?
CVE-2026-55580 was first published in the National Vulnerability Database on August 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55580 actively exploited?
CVE-2026-55580 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 95.4% of all scored CVEs.
What is the CVSS score of CVE-2026-55580?
CVE-2026-55580 has a CVSS v3 base score of 8.6 (NVD).
How do I remediate CVE-2026-55580?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55580, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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