What’s Vulnerable › Vulnerabilities

CVE-2026-44240: basic-ftp allows a malicious FTP server to cause client-side denial of service via unbounded multiline control response buffering

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-12 · updated 2026-10-26
• Weakness: CWE-400

Description

basic-ftp is an FTP client for Node.js. Prior to 5.3.1, basic-ftp is vulnerable to client-side denial of service when parsing FTP control-channel multiline responses. A malicious or compromised FTP server can send an unterminated multiline response during the initial FTP banner phase, before authentication. The client keeps appending attacker-controlled data into FtpContext._partialResponse and repeatedly reparses the accumulated buffer without enforcing a maximum control response size. As a result, an application using basic-ftp can remain stuck in connect() while memory and CPU usage grow under attacker-controlled input. This can lead to process-level denial of service, container OOM kills, worker restarts, queue backlog, or service degradation in applications that automatically connect to FTP endpoints. This vulnerability is fixed in 5.3.1.

Affected products

• patrickjuchli basic-ftp: before 5.3.1

References

• https://github.com/patrickjuchli/basic-ftp/security/advisories/GHSA-rpmf-866q-6p89
• https://github.com/patrickjuchli/basic-ftp/security/advisories/GHSA-rpmf-866q-6p89

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