GNU Emacs through 28.2 allows attackers to execute commands via shell metacharacters in the name of a source-code file, because lib-src/etags.c uses the system C library function in its implementation of the ctags program. For example, a victim may use the "ctags *" command (suggested in the ctags documentation) in a situation where the current working directory has contents that depend on untrusted input.
Stack-based buffer overflow in emacs allows user-assisted attackers to cause a denial of service (application crash) and possibly have unspecified other impact via a large precision value in an integer format string specifier to the format function, as demonstrated via a certain "emacs -batch -eval" command line.