CWE-785

Variant Abstraction Level
Pillar — Highest-level weakness category
Class — Abstract, language-independent
Base — Specific enough to detect
Variant — Tied to specific technology
Compound — Requires multiple weaknesses Incomplete MITRE CWE Status
Stable — Fully reviewed and complete
Draft — Under development, may change
Incomplete — Partially defined by MITRE
Deprecated — No longer recommended
Obsolete — Replaced by another CWE
Use of Path Manipulation Function without Maximum-sized Buffer

Description

The product invokes a function for normalizing paths or file names, but it provides an output buffer that is smaller than the maximum possible size, such as PATH_MAX.

Passing an inadequately-sized output buffer to a path manipulation function can result in a buffer overflow. Such functions include realpath(), readlink(), PathAppend(), and others.

Consequences

Integrity, Confidentiality, Availability — Modify Memory, Execute Unauthorized Code or Commands, DoS: Crash, Exit, or Restart

Mitigations

Phase: Implementation

Always specify output buffers large enough to handle the maximum-size possible result from path manipulation functions.

Detection

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)