SECURITY UPDATE: managesieve-login pre-auth excessive memory usage
DoS via oversized AUTHENTICATE initial response (ELSCVE-158960)
debian/patches/CVE-2026-27858.patch: verify the AUTHENTICATE initial
response size is not too large before allocating in
pigeonhole/src/managesieve-login/client-authenticate.c. Backport of
upstream pigeonhole commit 54f645225a8a; hunk context is this tree's
pre-cc1b8988 (unreformatted) layout.