Multiple heap-based buffer overflows in the ZRLE_DECODE function in common/rfb/zrleDecode.h in TigerVNC before 1.3.1, when NDEBUG is enabled, allow remote VNC servers to cause a denial of service (vncviewer crash) and possibly execute arbitrary code via vectors related to screen image rendering.

A flaw was discovered in the X.Org X server’s X Keyboard (Xkb) extension when handling client resource cleanup. The software frees certain data structures without properly detaching related resources, leading to a use-after-free condition. This can cause memory corruption or a crash when affected clients disconnect.

A flaw was identified in the X.Org X server’s X Keyboard (Xkb) extension where improper bounds checking in the XkbSetCompatMap() function can cause an unsigned short overflow. If an attacker sends specially crafted input data, the value calculation may overflow, leading to memory corruption or a crash.

A flaw was found in the X Record extension. The RecordSanityCheckRegisterClients function does not check for an integer overflow when computing request length, which allows a client to bypass length checks.

A flaw was found in the X Rendering extension's handling of animated cursors. If a client provides no cursors, the server assumes at least one is present, leading to an out-of-bounds read and potential crash.

A flaw was found in the Big Requests extension. The request length is multiplied by 4 before checking against the maximum allowed size, potentially causing an integer overflow and bypassing the size check.

A flaw was found in the RandR extension, where the RRChangeProviderProperty function does not properly validate input. This issue leads to an integer overflow when computing the total size to allocate.

A flaw was found in the X server's request handling. Non-zero 'bytes to ignore' in a client's request can cause the server to skip processing another client's request, potentially leading to a denial of service.