Vulnerability in diff-so-fancy software

CERT Polska has received a report about vulnerability in diff-so-fancy software and participated in coordination of its disclosure.

The vulnerabilityCVE-2026-50642: diff‑so‑fancy does not properly sanitize non‑SGR terminal control sequences before outputting diff data. The application only strips ANSI Select Graphic Rendition (SGR) sequences while allowing other control characters, including carriage return (\r) and escape sequences (e.g.,OSC,CSI), to pass through unsanitized.

An attacker can embed malicious control sequences in filenames, diff metadata, or file content that are rendered directly in the terminal during diff viewing. This can lead to output manipulation, including filename spoofing, terminal screen clearing, and clipboard injection via supported escape sequences.

Successful exploitation may mislead users during code review, alter terminal state, or result in unintended command execution through clipboard hijacking.

This issue has been fixed in the commit 9c81294.

We thank Michał Majchrowicz and Marcin Wyczechowski from AFINE Team for the responsible vulnerability report.