CWE-626 - Null Byte Interaction Error (Poison Null Byte)
- Abstraction:Variant
- Structure:Simple
- Status:Draft
- Release Date:2007-05-07
- Latest Modification Date:2023-06-29
Weakness Name
Null Byte Interaction Error (Poison Null Byte)
Description
The product does not properly handle null bytes or NUL characters when passing data between different representations or components.
A null byte (NUL character) can have different meanings across representations or languages. For example, it is a string terminator in standard C libraries, but Perl and PHP strings do not treat it as a terminator. When two representations are crossed - such as when Perl or PHP invokes underlying C functionality - this can produce an interaction error with unexpected results. Similar issues have been reported for ASP. Other interpreters written in C might also be affected. The poison null byte is frequently useful in path traversal attacks by terminating hard-coded extensions that are added to a filename. It can play a role in regular expression processing in PHP.
Common Consequences
Scope: Integrity
Impact: Unexpected State
