CWE-626: Null Byte Interaction Error (Poison Null Byte)
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.
Consequences
- Integrity: Unexpected State
How to prevent it
- Implementation: Remove null bytes from all incoming strings.
Recent advisories
- GHSA-xhjh-pmcv-23jw — Axios: Null Byte Injection via Reverse-Encoding in AxiosURLSearchParams
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