CVE-2026-55582

HIGHPre-NVD 8.48.4—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 91% 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
Elevated
8.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.4Exploit: Elevated riskExposed: 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, the default security.yaml allows /usr/bin/git, while security.go omits ! from containsShellMetacharacters and containsDangerousShellConstructs and applies no per-executable argument policy. A caller of the shell_exec MCP tool can provide the command argument /usr/bin/git -c alias.pwn=!, causing Git to create a shell alias and execute arbitrary OS commands as the mcp-shell process user. The default Docker image runs as mcpuser with Git installed and secure mode enabled, so the bypass is exploitable in the default deployment without additional authentication beyond MCP connectivity. This issue is fixed in version 0.6.0.

CVSS v3
8.4
EG Score
8.4(medium)
EG Risk
54(Track*)
EG Risk 54/100SSVC: 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
Severity84% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
0%
EPSS %ILE
9%
KEV
Not listed

Published

August 25, 2026

Last Modified

August 28, 2026

Advisory Details (4)

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

Secure Mode Allowlist Bypass via Git Shell Alias · Advisory · sonirico/mcp-shell · GitHub

https://github.com/sonirico/mcp-shell/security/advisories/GHSA-74hp-mggr-hv58
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_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_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

Vendor Advisories for CVE-2026-55582(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. 2026-08-28 23:28 UTCEG score recompute
  3. 2026-08-28 22:51 UTCEG score recompute
  4. 2026-08-28 21:41 UTCEPSS rescore
  5. 2026-08-28 00:57 UTCEG score recompute
  6. 2026-08-27 14:25 UTCEPSS rescore
  7. 2026-08-26 15:01 UTCEG score recompute
  8. 2026-08-26 14:46 UTCEPSS rescore
  9. 2026-08-25 16:23 UTCEG score recompute
  10. 2026-08-25 15:44 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-55582?
CVE-2026-55582 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 security.yaml allows /usr/bin/git, while security.go omits ! from containsShellMetacharacters and containsDangerousShellConstructs and applies no per-executable argument policy. A…
When was CVE-2026-55582 disclosed?
CVE-2026-55582 was first published in the National Vulnerability Database on August 25, 2026, with the most recent update on August 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55582 actively exploited?
CVE-2026-55582 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 91.0% of all scored CVEs.
What is the CVSS score of CVE-2026-55582?
CVE-2026-55582 has a CVSS v3 base score of 8.4 (NVD).
How do I remediate CVE-2026-55582?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55582, 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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