CVE-2021-36159: Freebsd Libfetch

Critical severity, CVSS 9.1. EPSS: 2.6% chance of exploitation in the next 30 days.

libfetch before 2021-07-26, as used in apk-tools, xbps, and other products, mishandles numeric strings for the FTP and HTTP protocols. The FTP passive mode implementation allows an out-of-bounds read because strtol is used to parse the relevant numbers into address bytes. It does not check if the line ends prematurely. If it does, the for-loop condition checks for the '\0' terminator one byte too late.

Affected products

• Freebsd Libfetch: before 2021-07-26 (fixed in 2021-07-26)

Published 2021-08-03. Last modified 2026-06-17.