How severe is CVE-2025-53109?

No CVSS score has been assigned to CVE-2025-53109 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2025-53109?

CVE-2025-53109 affects the following packages: @modelcontextprotocol/server-filesystem (npm), @modelcontextprotocol/server-filesystem (npm). Ecosystems affected: npm.

How do I fix CVE-2025-53109?

A fix is available for CVE-2025-53109; check the affected-versions list above or the advisory for the patched release of @modelcontextprotocol/server-filesystem, then make sure no transitive dependency still pins the vulnerable range.

How do I detect CVE-2025-53109 in my npm dependencies?

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

How do I mitigate CVE-2025-53109 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2025-53109 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-53109 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-2025-53109?

CVE-2025-53109 has an EPSS (Exploit Prediction Scoring System) score of 0.8%, placing it in the 56th 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-2025-53109?

CVE-2025-53109 is classified as CWE-59 (CWE-59). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2025-53109 published, and has it been updated?

CVE-2025-53109 was published on July 2, 2025 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.

📦 npm

Not in CISA KEV

CVE-2025-53109 — @modelcontextprotocol/ser…

Fix: modelcontextprotocol/servers@d00c60d

CVE-2025-53109 is a CWE-59 vulnerability in @modelcontextprotocol/server-filesystem. A fix is available for @modelcontextprotocol/server-filesystem — see the affected versions and patch details below.

Model Context Protocol Servers Vulnerable to Path Validation Bypass via Prefix Matching and Symlink Handling

Also known asGHSA-q66q-fx2p-7w4m

Published

Jul 2, 2025

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

1 / 2

Exploits

None indexed

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-53109.

EPSS Exploitation Probability

via FIRST.org ↗

0.8%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs56th percentile — riskier than 56% of all scored CVEsHighest risk

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

Real-World Exposure

2 pkgs 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.

49other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

@modelcontextprotocol/server-filesystemnpm

1.3Mdownloads / week

Description

Model Context Protocol Servers is a collection of reference implementations for the model context protocol (MCP). Versions of Filesystem prior to 0.6.4 or 2025.7.01 could allow access to unintended files via symlinks within allowed directories. Users are advised to upgrade to 0.6.4 or 2025.7.01 resolve.

Affected Packages

2 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@modelcontextprotocol/server-filesystem`	all versions	No fix
📦npm	`@modelcontextprotocol/server-filesystem`	≥ 2025.1.14&&< 2025.7.1	2025.7.1`npm install @modelcontextprotocol/server-filesystem@2025.7.1`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @modelcontextprotocol/server-filesystem, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
A fix is available for CVE-2025-53109; check the affected-versions list above or the advisory for the patched release of @modelcontextprotocol/server-filesystem, then make sure no transitive dependency still pins the vulnerable range.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

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