GNU libidn before 1.44 is prone to out-of-bounds reads of uninitialized memory in the ToUnicode APIs because of mishandling in idnatounicodeinternal. The affected code is not present in libidn2.

idn in GNU libidn before 1.33 might allow remote attackers to obtain sensitive memory information by reading a zero byte as input, which triggers an out-of-bounds read.

idn in libidn before 1.33 might allow remote attackers to obtain sensitive memory information by reading a zero byte as input, which triggers an out-of-bounds read, a different vulnerability than CVE-2015-8948.

The idnatoascii4i function in lib/idna.c in libidn before 1.33 allows context-dependent attackers to cause a denial of service (out-of-bounds read and crash) via 64 bytes of input.

The stringpreputf8nfkcnormalize function in lib/nfkc.c in libidn before 1.33 allows context-dependent attackers to cause a denial of service (out-of-bounds read and crash) via crafted UTF-8 data.

The stringpreputf8toucs4 function in libin before 1.31, as used in jabberd2, allows context-dependent attackers to read system memory and possibly have other unspecified impact via invalid UTF-8 characters in a string, which triggers an out-of-bounds read.