:tocdepth: 3

===============================
Cyrus IMAP 3.0.16 Release Notes
===============================

.. IMPORTANT::

    This is a bug-fix release in the 3.0 series.

    Refer to the Cyrus IMAP 3.0.0 Release Notes for important information
    about the 3.0 series, including upgrading instructions.

Download via HTTPS:

    *   https://github.com/cyrusimap/cyrus-imapd/releases/download/cyrus-imapd-3.0.16/cyrus-imapd-3.0.16.tar.gz
    *   https://github.com/cyrusimap/cyrus-imapd/releases/download/cyrus-imapd-3.0.16/cyrus-imapd-3.0.16.tar.gz.sig


.. _relnotes-3.0.16-changes:

Changes Since 3.0.15
====================

Security fixes:
---------------

* Fixed :cve:`CVE-2021-33582`: Certain user inputs are used as hash table keys during
  processing.  A poorly chosen string hashing algorithm meant that the user
  could control which bucket their data was stored in, allowing a malicious
  user to direct many inputs to a single bucket.  Each subsequent insertion to
  the same bucket requires a strcmp of every other entry in it.  At tens of
  thousands of entries, each new insertion could keep the CPU busy in a strcmp
  loop for minutes.

  The string hashing algorithm has been replaced with a better one, and now
  also uses a random seed per hash table, so malicious inputs cannot be
  precomputed.

  Discovered by Matthew Horsfall, Fastmail

Build fixes
-----------

* Fixed: expired test certificates caused unit test failures
* Fixed: various warnings raised by newer compilers

Bug fixes
---------

* Fixed: crash when looking up entries in zero-sized hash tables
* Fixed: deduplicated code in hash_del (thanks Дилян Палаузов)
* Fixed :issue:`3456`: per-server annotations were unable to replicate
