basic-ftp: Quadratic-time CPU denial of service in Client.list() Unix directory-listing parser (RE_LINE backtracking)

[ Why it matters ]Priority signals

• Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

basic-ftp is an FTP client for Node.js. Prior to 6.2.1, Client.list() can be forced by a malicious or compromised FTP server to spend quadratic CPU time parsing a directory listing because the RE_LINE expression in src/parseListUnix.ts backtracks across adjacent variable-length owner and group fields when a long Unix-style line has a valid prefix but cannot satisfy the later size and date fields. parseList() selects a parser from the last nonblank line and then applies it to every line, so a normal final line can select the Unix parser while an earlier crafted line blocks the Node.js event loop and freezes the process. This issue is fixed in version 6.2.1.

[ Fixes ]Fixes and patches

• basic-ftp 6.2.1Fixed version · GitHub Advisories · npm package basic-ftp: upgrade to 6.2.1 or later (affected <= 6.2.0)

[ Packages ]Affected open-source packages

• basic-ftp npmAffected <= 6.2.0 · fixed in 6.2.1 · GHSA-c475-qrg2-pj4r

[ References ]References

• github.com/patrickjuchli/basic-ftp/commit/d0d9e07c56e519587bb50532ac6eadbb0cb0cfe9
• github.com/patrickjuchli/basic-ftp/releases/tag/v6.2.1
• github.com/patrickjuchli/basic-ftp/security/advisories/GHSA-c475-qrg2-pj4r