Description
In elisp-mode.el in GNU Emacs before 30.1, a user who chooses to invoke elisp-completion-at-point (for code completion) on untrusted Emacs Lisp source code can trigger unsafe Lisp macro expansion that allows attackers to execute arbitrary code. (This unsafe expansion also occurs if a user chooses to enable on-the-fly diagnosis that byte compiles untrusted Emacs Lisp source code.)
References
lists.debian.org/debian-lts-announce/2025/02/msg00033.html
git.savannah.gnu.org/cgit/emacs.git/tree/ChangeLog.4
git.savannah.gnu.org/cgit/emacs.git/tag/?h=emacs-30.0.92
eshelyaron.com/...ry-code-execution-and-how-to-avoid-it.html
yhetil.org/...qH34UbYU56_t6t2Er0YEh1Sb7-W=hg@mail.gmail.com/
news.ycombinator.com/item?id=42256409
git.savannah.gnu.org/...emacs.git/tree/etc/NEWS?h=emacs-30.1