An invalid free in mbdetectorder can cause the application to crash or potentially result in remote code execution. This issue affects HHVM versions prior to 3.30.12, all versions between 4.0.0 and 4.8.5, all versions between 4.9.0 and 4.23.1, as well as 4.24.0, 4.25.0, 4.26.0, 4.27.0, 4.28.0, and 4.28.1.

Insufficient boundary checks when processing a string in mberegreplace allows access to out-of-bounds memory. This issue affects HHVM versions prior to 3.30.12, all versions between 4.0.0 and 4.8.5, all versions between 4.9.0 and 4.23.1, as well as 4.24.0, 4.25.0, 4.26.0, 4.27.0, 4.28.0, and 4.28.1.

Various APC functions accept keys containing null bytes as input, leading to premature truncation of input. This issue affects HHVM versions prior to 3.30.12, all versions between 4.0.0 and 4.8.5, all versions between 4.9.0 and 4.23.1, as well as 4.24.0, 4.25.0, 4.26.0, 4.27.0, 4.28.0, and 4.28.1.

Insufficient boundary checks when formatting numbers in numberformat allows read/write access to out-of-bounds memory, potentially leading to remote code execution. This issue affects HHVM versions prior to 3.30.10, all versions between 4.0.0 and 4.8.5, all versions between 4.9.0 and 4.18.2, and versions 4.19.0, 4.19.1, 4.20.0, 4.20.1, 4.20.2, 4.21.0, 4.22.0, 4.23.0.

Insufficient boundary checks when processing the JPEG APP12 block marker in the GD extension could allow access to out-of-bounds memory via a maliciously constructed invalid JPEG input. This issue affects HHVM versions prior to 3.30.9, all versions between 4.0.0 and 4.8.3, all versions between 4.9.0 and 4.15.2, and versions 4.16.0 to 4.16.3, 4.17.0 to 4.17.2, 4.18.0 to 4.18.1, 4.19.0, 4.20.0 to 4.20.1.

Insufficient boundary checks when processing MSOFx markers from JPEG headers in the GD extension could allow access to out-of-bounds memory via a maliciously constructed invalid JPEG input. This issue affects HHVM versions prior to 3.30.9, all versions between 4.0.0 and 4.8.3, all versions between 4.9.0 and 4.15.2, and versions 4.16.0 to 4.16.3, 4.17.0 to 4.17.2, 4.18.0 to 4.18.1, 4.19.0, 4.20.0 to 4.20.1.

Insufficient boundary checks for the strrpos and strripos functions allow access to out-of-bounds memory. This affects all supported versions of HHVM (4.0.3, 3.30.4, and 3.27.7 and below).

HHVM, when used with FastCGI, would bind by default to all available interfaces. This behavior could allow a malicious individual unintended direct access to the application, which could result in information disclosure. 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.