There is an updated pull request by shahab-vahedi against master on the void-packages repository

https://github.com/shahab-vahedi/void-packages expect-fix
https://github.com/void-linux/void-packages/pull/26861

expect 5.45.4_3: Fix the buffer overlow while logging
There is a buffer overflow issue with "expect" when you run it
with "--debug" flag and the expected string is too big [1].

This patch was already proposed 7 years ago [2] but never found
its away upstream. Other distros also fix it locally [3]. It's
time we have it fixed in Void Linux as well.

[1] Bug 26986 - *** buffer overflow detected ***: expect terminated
https://sourceware.org/bugzilla/show_bug.cgi?id=26986

[2] Expect / Bugs / #95 buffer overflow in exp_log.c
https://sourceforge.net/p/expect/bugs/95/

[3] fedora fixing the overflow in expect
https://src.fedoraproject.org/rpms/expect/blob/master/f/expect-5.45-exp-log-buf-overflow.patch

A patch file from https://github.com/void-linux/void-packages/pull/26861.patch is attached