Security Digest · Vulnerability record
CVE-2026-27699: Basic FTP has Path Traversal Vulnerability in its downloadToDir() method
The basic-ftp FTP client library for Node.js contains a path traversal vulnerability (CWE-22) in versions prior to 5.2.0 in the downloadToDir() method.
CVSS 9.1 Critical EPSS 1.0% · p63
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 1.0%, percentile 63: FIRST’s model estimates a 1.0% chance of exploitation activity in the next 30 days, higher than 63% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
basic-ftp(npm) < 5.2.0, fixed in 5.2.0. Check your lockfile, including transitive dependencies.
What it is
The basic-ftp FTP client library for Node.js contains a path traversal vulnerability (CWE-22) in versions prior to 5.2.0 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. Version 5.2.0 patches the issue.
From the GitHub advisory
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
Vulnerable Code
File: src/Client.ts:707
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
Weakness type: CWE-22.
Product: basic-ftp (npm) · Assigned by: GitHub_M · Published: 2026-02-25
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| npm | basic-ftp | < 5.2.0 | 5.2.0 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| patrickjuchli | basic-ftp | < 5.2.0 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H |
| GitHub | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 1.03% probability of exploitation activity in the next 30 days; percentile 63.
Timeline
- — CVE record published by GitHub_M
- — GitHub-reviewed advisory GHSA-5rq4-664w-9x2c published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-5rq4-664w-9x2c github.com
- CVE.org record CVE-2026-27699 cve.org
- NVD entry CVE-2026-27699 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- github.com github.com