Off-by-one error in the QUtf8Decoder::toUnicode function in Trolltech Qt 3 allows context-dependent attackers to cause a denial of service (crash) via a crafted Unicode string that triggers a heap-based buffer overflow. NOTE: Qt 4 has the same error in the QUtf8Codec::convertToUnicode function, but it is not exploitable.

Qt before 3.3.4 searches the BUILD_PREFIX directory, which could be world-writable, to load shared libraries regardless of the LD_LIBRARY_PATH environment variable, which allows local users to execute arbitrary programs.