Call to the scrypt_enc() function in HHVM can lead to heap corruption by using specifically crafted parameters (N, r and p). This happens if the parameters are configurable by an attacker for instance by providing the output of scrypt_enc() in a context where Hack/PHP code would attempt to verify it by re-running scrypt_enc() with the same parameters. This could result in information disclosure, memory being overwriten or crashes of the HHVM process. This issue affects versions 4.3.0, 4.4.0, 4.5.0, 4.6.0, 4.7.0, 4.8.0, versions 3.30.5 and below, and all versions in the 4.0, 4.1, and 4.2 series.

Cross-site scripting (XSS) vulnerability in the WddxPacket::recursiveAddVar function in HHVM (aka the HipHop Virtual Machine) before 3.5.0 allows remote attackers to inject arbitrary web script or HTML via a crafted string to the wddx_serialize_value function.

The HashContext class in hphp/runtime/ext/ext_hash.cpp in Facebook HipHop Virtual Machine (HHVM) before 3.3.0 incorrectly expects that a certain key string uses '\0' for termination, which allows remote attackers to obtain sensitive information by leveraging read access beyond the end of the string, and makes it easier for remote attackers to defeat cryptographic protection mechanisms by leveraging truncation of a string containing an internal '\0' character.

Integer overflow in the string_chunk_split function in hphp/runtime/base/zend-string.cpp in Facebook HipHop Virtual Machine (HHVM) before 3.3.0 allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via crafted arguments to the chunk_split function.

The mcrypt_create_iv function in hphp/runtime/ext/mcrypt/ext_mcrypt.cpp in Facebook HipHop Virtual Machine (HHVM) before 3.3.0 does not seed the random number generator, which makes it easier for remote attackers to defeat cryptographic protection mechanisms by leveraging the use of a single initialization vector.

Facebook HipHop Virtual Machine (HHVM) before 3.1.0 does not drop supplemental group memberships within hphp/util/capability.cpp and hphp/util/light-process.cpp, which allows remote attackers to bypass intended access restrictions by leveraging group permissions for a file or directory.

CRLF injection vulnerability in the LightProcess protocol implementation in hphp/util/light-process.cpp in Facebook HipHop Virtual Machine (HHVM) before 2.4.2 allows remote attackers to execute arbitrary commands by entering a \n (newline) character before the end of a string.