CWE-186: Overly Restrictive Regular Expression
CWE版本: 4.18
更新日期: 2025-09-09
弱点描述
A regular expression is overly restrictive, which prevents dangerous values from being detected.
扩展描述
This weakness is not about regular expression complexity. Rather, it is about a regular expression that does not match all values that are intended. Consider the use of a regexp to identify acceptable values or to spot unwanted terms. An overly restrictive regexp misses some potentially security-relevant values leading to either false positives *or* false negatives, depending on how the regexp is being used within the code. Consider the expression /[0-8]/ where the intention was /[0-9]/. This expression is not "complex" but the value "9" is not matched when maybe the programmer planned to check for it.
常见后果
影响范围: Access Control
技术影响: Bypass Protection Mechanism
潜在缓解措施
阶段: Implementation
描述: Regular expressions can become error prone when defining a complex language even for those experienced in writing grammars. Determine if several smaller regular expressions simplify one large regular expression. Also, subject your regular expression to thorough testing techniques such as equivalence partitioning, boundary value analysis, and robustness. After testing and a reasonable confidence level is achieved, a regular expression may not be foolproof. If an exploit is allowed to slip through, then record the exploit and refactor your regular expression.
观察示例
参考: CVE-2005-1604
MIE. ".php.ns" bypasses ".php$" regexp but is still parsed as PHP by Apache. (manipulates an equivalence property under Apache)
引入模式
| 阶段 | 说明 |
|---|---|
| Implementation | - |
适用平台
编程语言
分类映射
| 分类名称 | 条目ID | 条目名称 | 映射适配度 |
|---|---|---|---|
| PLOVER | - | Overly Restrictive Regular Expression | - |