How severe is CVE-2026-5327?

No CVSS score has been assigned to CVE-2026-5327 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-5327?

CVE-2026-5327 affects the following packages: fast-filesystem-mcp (npm). Ecosystems affected: npm.

How do I fix CVE-2026-5327?

The records we use list no patched version of fast-filesystem-mcp for CVE-2026-5327. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

How do I detect CVE-2026-5327 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fast-filesystem-mcp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-5327 if there is no patch (or I can't update yet)?

Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Is CVE-2026-5327 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-5327 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-5327?

CVE-2026-5327 has an EPSS (Exploit Prediction Scoring System) score of 1.2%, placing it in the 69th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-5327?

CVE-2026-5327 is classified as CWE-74 (CWE-74), CWE-77 (CWE-77). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-5327 published, and has it been updated?

CVE-2026-5327 was published on April 2, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-5327: fast-filesystem-mcp Command Injection

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-5327.

EPSS Exploitation Probability

via FIRST.org ↗

1.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs69th percentile — riskier than 69% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

0other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

fast-filesystem-mcpnpm

176downloads / week

Description

A security flaw has been discovered in efforthye fast-filesystem-mcp up to 3.5.1. The affected element is the function handleGetDiskUsage of the file src/index.ts. Performing a manipulation results in command injection. The attack is possible to be carried out remotely. The exploit has been released to the public and may be used for attacks. The project was informed of the problem early through an issue report but has not responded yet.

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
📦npm	`fast-filesystem-mcp`	all versions	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fast-filesystem-mcp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
The records we use list no patched version of fast-filesystem-mcp for CVE-2026-5327. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.
Mitigate without a patch
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Frequently Asked Questions

A security flaw has been discovered in efforthye fast-filesystem-mcp up to 3.5.1. The affected element is the function handleGetDiskUsage of the file src/index.ts. Performing a manipulation results in command injection. The attack is possible to be carried out remotely. The exploit has been released to the public and may be used for attacks. The project was informed of the problem early through an issue report but has not responded yet.

O3 Security · Impact-Aware SCA

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CVE-2026-5327 — fast-filesystem-mcp