Patches directories for all supported versions, plus a security announcements list (English).
Microsoft-product-related security headlines and bulletins.
Security advisories and patches.
Security and other patches for AIX. Note that this is an FTP site.
You need the "fixdist" program to install AIX patches.
Details of current and archive security advisories. Includes mailing list and a security FAQ.
Patch Security Matrix, list of obsolete patches, patch checksums.
Advisories and patches.
Only if you've built KDE yourself; otherwise probably available from your linux distribution vendor's patches directory. Note this is an FTP site.
Security patches for all releases. Note this is an FTP site.