The resolveImplicitLevels function in common/ubidi.c in the Unicode Bidirectional Algorithm implementation in ICU4C in International Components for Unicode (ICU) before 55.1 uses an integer data type that is inconsistent with a header file, which allows remote attackers to cause a denial of service (incorrect malloc followed by invalid free) or possibly execute arbitrary code via crafted text.

The resolveImplicitLevels function in common/ubidi.c in the Unicode Bidirectional Algorithm implementation in ICU4C in International Components for Unicode (ICU) before 55.1 does not properly track directionally isolated pieces of text, which allows remote attackers to cause a denial of service (heap-based buffer overflow) or possibly execute arbitrary code via crafted text.

The Regular Expressions package in International Components for Unicode (ICU) 52 before SVN revision 292944, as used in Google Chrome before 40.0.2214.91, allows remote attackers to cause a denial of service (memory corruption) or possibly have unspecified other impact via vectors related to a zero-length quantifier.

The collator implementation in i18n/ucol.cpp in International Components for Unicode (ICU) 52 through SVN revision 293126, as used in Google Chrome before 40.0.2214.91, does not initialize memory for a data structure, which allows remote attackers to cause a denial of service or possibly have unspecified other impact via a crafted character sequence.

The Regular Expressions package in International Components for Unicode (ICU) 52 before SVN revision 292944, as used in Google Chrome before 40.0.2214.91, allows remote attackers to cause a denial of service (memory corruption) or possibly have unspecified other impact via vectors related to a look-behind expression.

rxvt-unicode before 9.20 does not properly handle OSC escape sequences, which allows user-assisted remote attackers to manipulate arbitrary X window properties and execute arbitrary commands.

Stack-based buffer overflow in the _canonicalize function in common/uloc.c in International Components for Unicode (ICU) before 49.1 allows remote attackers to execute arbitrary code via a crafted locale ID that is not properly handled during variant canonicalization.

rxvt 2.6.4 opens a terminal window on :0 if the DISPLAY environment variable is not set, which might allow local users to hijack X11 connections. NOTE: it was later reported that rxvt-unicode, mrxvt, aterm, multi-aterm, and wterm are also affected. NOTE: realistic attack scenarios require that the victim enters a command on the wrong machine.

Heap-based buffer overflow in the doInterval function in regexcmp.cpp in libicu in International Components for Unicode (ICU) 3.8.1 and earlier allows context-dependent attackers to cause a denial of service (memory consumption) and possibly have unspecified other impact via a regular expression that writes a large amount of data to the backtracking stack. NOTE: some of these details are obtained from third party information.

libicu in International Components for Unicode (ICU) 3.8.1 and earlier attempts to process backreferences to the nonexistent capture group zero (aka \0), which might allow context-dependent attackers to read from, or write to, out-of-bounds memory locations, related to corruption of REStackFrames.