How severe is GHSA-5rq4-664w-9x2c?

GHSA-5rq4-664w-9x2c has a CVSS score of 9.1/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by GHSA-5rq4-664w-9x2c?

GHSA-5rq4-664w-9x2c affects the following packages: basic-ftp (npm). Ecosystems affected: npm.

How do I fix GHSA-5rq4-664w-9x2c?

Update basic-ftp to 5.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-5rq4-664w-9x2c is resolved across your whole dependency graph.

How do I detect GHSA-5rq4-664w-9x2c in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for basic-ftp. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-5rq4-664w-9x2c 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.

How does O3 Security protect against GHSA-5rq4-664w-9x2c?

O3 pinpoints whether GHSA-5rq4-664w-9x2c is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-5rq4-664w-9x2c actively exploited in the wild?

No public exploit code has been indexed for GHSA-5rq4-664w-9x2c 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 GHSA-5rq4-664w-9x2c?

GHSA-5rq4-664w-9x2c has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 40th 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 GHSA-5rq4-664w-9x2c?

GHSA-5rq4-664w-9x2c is classified as Path Traversal (CWE-22). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-5rq4-664w-9x2c published, and has it been updated?

GHSA-5rq4-664w-9x2c was published on February 25, 2026 and was last updated on February 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

GHSA-5rq4-664w-9x2c

CRITICAL

Basic FTP has Path Traversal Vulnerability in its downloadToDir() method

Also known asCVE-2026-27699

Published

Feb 25, 2026

Updated

Feb 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk40th percentile+0.38%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

📦basic-ftp

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

The basic-ftp library contains a path traversal vulnerability in the downloadToDir() method. A malicious FTP server can send directory listings with filenames containing path traversal sequences (../) that cause files to be written outside the intended download directory.

Source-to-Sink Flow

1. SOURCE: FTP server sends LIST response
└─> "-rw-r--r-- 1 user group 1024 Jan 20 12:00 ../../../etc/passwd"

2. PARSER: parseListUnix.ts:100 extracts filename
└─> file.name = "../../../etc/passwd"

3. VALIDATION: parseListUnix.ts:101 checks
└─> if (name === "." || name === "..") ❌ (only filters exact matches)
└─> "../../../etc/passwd" !== "." && !== ".." ✅ PASSES

4. SINK: Client.ts:707 uses filename directly
└─> const localPath = join(localDirPath, file.name)
└─> join("/safe/download", "../../../etc/passwd")
└─> Result: "/safe/download/../../../etc/passwd" → resolves to "/etc/passwd"

5. FILE WRITE: Client.ts:512 opens file
└─> fsOpen(localPath, "w") → writes to /etc/passwd (outside intended directory)

Vulnerable Code

File: src/Client.ts:707

protected async _downloadFromWorkingDir(localDirPath: string): Promise<void> {
await ensureLocalDirectory(localDirPath)
for (const file of await this.list()) {
const localPath = join(localDirPath, file.name) // ⚠️ VULNERABLE
// file.name comes from untrusted FTP server, no sanitization
await this.downloadTo(localPath, file.name)
}
}

Root Cause: - Parser validation (parseListUnix.ts:101) only filters exact . or .. entries - No sanitization of ../ sequences in filenames

path.join() doesn't prevent traversal, fs.open() resolves paths

Impact

A malicious FTP server can: - Write files to arbitrary locations on the client filesystem - Overwrite critical system files (if user has write access) - Potentially achieve remote code execution

Affected Versions

Tested: v5.1.0
Likely: All versions (code pattern exists since initial implementation)

Mitigation

Workaround: Do not use downloadToDir() with untrusted FTP servers.

Fix: Sanitize filenames before use:

import { basename } from 'path'

// In _downloadFromWorkingDir:
const sanitizedName = basename(file.name) // Strip path components
const localPath = join(localDirPath, sanitizedName)

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`basic-ftp`	all versions	5.2.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for basic-ftp. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update basic-ftp to 5.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-5rq4-664w-9x2c is resolved across your whole dependency graph.
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.
How O3 protects you
O3 pinpoints whether GHSA-5rq4-664w-9x2c is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-5rq4-664w-9x2c. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

The `basic-ftp` library contains a path traversal vulnerability in the `downloadToDir()` method. A malicious FTP server can send directory listings with filenames containing path traversal sequences (`../`) that cause files to be written outside the intended download directory. ## Source-to-Sink Flow ``` 1. SOURCE: FTP server sends LIST response └─> "-rw-r--r-- 1 user group 1024 Jan 20 12:00 ../../../etc/passwd" 2. PARSER: parseListUnix.ts:100 extracts filename └─> file.name = "../../../etc/passwd" 3. VALIDATION: parseListUnix.ts:101 checks └─> if (name === "." || name === "..") ❌ (only f

O3 Security · Impact-Aware SCA

Is GHSA-5rq4-664w-9x2c in your dependencies?

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