KDE kmail before 5.5.2 and messagelib before 5.5.2, as distributed in KDE Applications before 17.04.2, do not ensure that a plugin's sign/encrypt action occurs during use of the Send Later feature, which allows remote attackers to obtain sensitive information by sniffing the network.

Heap-based buffer overflow in the progressive PNG Image loader (decoders/pngloader.cpp) in KHTML in KDE 4.0.x up to 4.0.3 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted image.

startkdeinit in KDE 3.5.5 through 3.5.9, when installed setuid root, allows local users to cause a denial of service and possibly execute arbitrary code via "user-influenceable input" (probably command-line arguments) that cause startkdeinit to send SIGUSR1 signals to other processes.

Screen savers in KDE beta 3 allows local users to overwrite arbitrary files via a symlink attack on the .kss.pid file.