xorg-x11-server before 1.19.5 was vulnerable to integer overflow in ProcDbeGetVisualInfo function allowing malicious X client to cause X server to crash or possibly execute arbitrary code.

xorg-x11-server before 1.19.5 was missing extra length validation in ProcEstablishConnection function allowing malicious X client to cause X server to crash or possibly execute arbitrary code.

xorg-x11-server before 1.19.5 was missing length validation in XFree86 DRI extension allowing malicious X client to cause X server to crash or possibly execute arbitrary code.

xorg-x11-server before 1.19.5 was missing length validation in X-Resource extension allowing malicious X client to cause X server to crash or possibly execute arbitrary code.

xorg-x11-server before 1.19.5 was missing length validation in XFree86 DGA extension allowing malicious X client to cause X server to crash or possibly execute arbitrary code.

In the pcfGetProperties function in bitmap/pcfread.c in libXfont through 1.5.2 and 2.x before 2.0.2, a missing boundary check (for PCF files) could be used by local attackers authenticated to an Xserver for a buffer over-read, for information disclosure or a crash of the X server.

In the PatternMatch function in fontfile/fontdir.c in libXfont through 1.5.2 and 2.x before 2.0.2, an attacker with access to an X connection can cause a buffer over-read during pattern matching of fonts, leading to information disclosure or a crash (denial of service). This occurs because '\0' characters are incorrectly skipped in situations involving ? characters.

In X.Org Server (aka xserver and xorg-server) before 1.19.4, an attacker authenticated to an X server with the X shared memory extension enabled can cause aborts of the X server or replace shared memory segments of other X clients in the same session.

In X.Org Server (aka xserver and xorg-server) before 1.19.4, a local attacker authenticated to the X server could overflow a global buffer, causing crashes of the X server or potentially other problems by injecting large or malformed XKB related atoms and accessing them via xkbcomp.

Uninitialized data in endianness conversion in the XEvent handling of the X.Org X Server before 2017-06-19 allowed authenticated malicious users to access potentially privileged data from the X server.