The dechunk filter in PHP 5.3 through 5.3.2, when decoding an HTTP chunked encoding stream, allows context-dependent attackers to cause a denial of service (crash) and possibly trigger memory corruption via a negative chunk size, which bypasses a signed comparison, related to an integer overflow in the chunk size decoder.
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
| Link | Tags |
|---|---|
| http://php-security.org/2010/05/02/mops-2010-003-php-dechunk-filter-signed-comparison-vulnerability/index.html | broken link exploit |
| http://lists.opensuse.org/opensuse-security-announce/2010-09/msg00006.html | mailing list vendor advisory |