Vulnerability in entr software

CERT Polska has received a report about vulnerability in eradman entr software and participated in coordination of its disclosure.

The vulnerabilityCVE-2026-18370: entr is vulnerable to Heap-based buffer overflow inrun_utility()function. The function allocates a fixed-size heap buffer usingmalloc(ARG_MAX)and copies command-line arguments into it. It advances the destination pointer based on the return value ofstrlcpy(), which returns the total length of the source string rather than the number of bytes written. When the buffer is exactly filled, the remaining size underflows as an unsignedsize_t, causing subsequent copies to write out of bounds. This can be triggered by supplying command-line arguments whose combined length fills the buffer, or via the/_substitution feature which expands a short token into a longer pathname at runtime. The local attacker can cause memory corruption, process abort, and denial of service.

This issue was fixed in commit 2467fe0

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