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 , 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.
CVE-2026-55581
HIGHPre-NVD 8.48.4Elevated
EchelonGraph scoreLOW confidence
This high-severity CVE scores 8.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). 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: secondary
8.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: —CVSS: 8.4Exploit: Elevated riskExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 8.4
- EG Score
- 8.4(low)
- EG Risk
- 38(Track*)EG Risk 38/100SSVC: 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 computedSeverity84% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Watch closely — could escalate to Attend. - EPSS PROB
- —
- EPSS %ILE
- —
- 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, github_commit, github_pr, github_release.
github Patch Available🟡 PoC Available
Secure Mode Allowlist Bypass via Default `/bin/bash` Executable · Advisory · sonirico/mcp-shell · GitHub
https://github.com/sonirico/mcp-shell/security/advisories/GHSA-3x77-wg38-92r3github_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/v0.6.0github_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/16github_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/f31377fce6ec31114e5a4398c0e5270552bce09fVendor Advisories for CVE-2026-55581(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(3)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 4× in last 7d / 4× 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.
- 2026-08-25 19:21 UTCEG score recompute
- 2026-08-25 19:10 UTCEG score recompute
- 2026-08-25 16:23 UTCEG score recompute
- 2026-08-25 15:44 UTCEG score recompute
Related CVEs(same CWE)
Same CWE
10 shownCWE-78
- CVE-2009-20011EG 10.0CRITICAL
- CVE-2011-10017EG 10.0CRITICAL
- CVE-2012-1166EG 10.0EPSS p91HIGH
- CVE-2012-2976EG 10.0EPSS p92HIGH
- CVE-2012-2953EG 10.0EPSS p99HIGH
- CVE-2011-4502EG 10.0EPSS p92HIGH
- CVE-2011-2148EG 10.0EPSS p92HIGH
- CVE-2011-0382EG 10.0EPSS p90HIGH
- CVE-2011-0381EG 10.0EPSS p92HIGH
- CVE-2011-0372EG 10.0HIGH
Frequently asked(4)
What is CVE-2026-55581?
CVE-2026-55581 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, the default Docker security.yaml includes /bin/bash in allowedexecutables, while security.go validates only the first token and checkBlockedPatternsAndCommands does not reject the shell…
When was CVE-2026-55581 disclosed?
CVE-2026-55581 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.
What is the CVSS score of CVE-2026-55581?
CVE-2026-55581 has a CVSS v3 base score of 8.4 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-55581?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55581, 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
Explore the affected products and dependency analysis for CVE-2026-55581
Is Your Infrastructure Affected by CVE-2026-55581?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.