#exim is tracking this in their bug report at https://bugs.exim.org/show_bug.cgi?id=3063 and a fix has been committed at https://git.exim.org/exim.git/commit/5bb786d5ad568a88d50d15452aacc8404047e5ca - thx @QuatermassTools for the info! https://infosec.exchange/@QuatermassTools/111637108410087826
For #sendmail some mitigation details at https://www.openwall.com/lists/oss-security/2023/12/21/7