In PHP versions 7.2.x below 7.2.31, 7.3.x below 7.3.18 and 7.4.x below 7.4.6, when HTTP file uploads are allowed, supplying overly long filenames or field names could lead PHP engine to try to allocate oversized memory storage, hit the memory limit and stop processing the request, without cleaning up temporary files created by upload request. This potentially could lead to accumulation of uncleaned temporary files exhausting the disk space on the target server.
In PHP versions 7.2.x below 7.2.30, 7.3.x below 7.3.17 and 7.4.x below 7.4.5, if PHP is compiled with EBCDIC support (uncommon), urldecode() function can be made to access locations past the allocated memory, due to erroneously using signed numbers as array indexes.
PHP 7.x through 7.1.5 allows remote attackers to cause a denial of service (buffer overflow and application crash) or possibly have unspecified other impact via a long string because of an Integer overflow in mysqli_real_escape_string.
The zend_string_extend function in Zend/zend_string.h in PHP through 7.1.5 does not prevent changes to string objects that result in a negative length, which allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact by leveraging a script's use of .= with a long string.
Buffer overflow in the radius_get_vendor_attr function in the Radius extension before 1.2.7 for PHP allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a large Vendor Specific Attributes (VSA) length value.
The parse_str function in (1) PHP, (2) Hardened-PHP, and (3) Suhosin, when called without a second parameter, might allow remote attackers to overwrite arbitrary variables by specifying variable names and values in the string to be parsed. NOTE: it is not clear whether this is a design limitation of the function or a bug in PHP, although it is likely to be regarded as a bug in Hardened-PHP and Suhosin.