CWE-786: Access of Memory Location Before Start of Buffer
CWE版本: 4.18
更新日期: 2025-09-09
弱点描述
The product reads or writes to a buffer using an index or pointer that references a memory location prior to the beginning of the buffer.
扩展描述
This typically occurs when a pointer or its index is decremented to a position before the buffer, when pointer arithmetic results in a position before the beginning of the valid memory location, or when a negative index is used.
常见后果
影响范围: Confidentiality
技术影响: Read Memory
说明: For an out-of-bounds read, the attacker may have access to sensitive information. If the sensitive information contains system details, such as the current buffer's position in memory, this knowledge can be used to craft further attacks, possibly with more severe consequences.
影响范围: Integrity Availability
技术影响: Modify Memory DoS: Crash, Exit, or Restart
说明: Out of bounds memory access will very likely result in the corruption of relevant memory, and perhaps instructions, possibly leading to a crash.
影响范围: Integrity
技术影响: Modify Memory Execute Unauthorized Code or Commands
说明: If the corrupted memory can be effectively controlled, it may be possible to execute arbitrary code. If the corrupted memory is data rather than instructions, the system will continue to function with improper changes, possibly in violation of an implicit or explicit policy.
检测方法
方法: Fuzzing
Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.
有效性: High
观察示例
参考: CVE-2002-2227
Unchecked length of SSLv2 challenge value leads to buffer underflow.
参考: CVE-2007-4580
Buffer underflow from a small size value with a large buffer (length parameter inconsistency, CWE-130)
参考: CVE-2007-1584
Buffer underflow from an all-whitespace string, which causes a counter to be decremented before the buffer while looking for a non-whitespace character.
参考: CVE-2007-0886
Buffer underflow resultant from encoded data that triggers an integer overflow.
参考: CVE-2006-6171
Product sets an incorrect buffer size limit, leading to "off-by-two" buffer underflow.
参考: CVE-2006-4024
Negative value is used in a memcpy() operation, leading to buffer underflow.
参考: CVE-2004-2620
Buffer underflow due to mishandled special characters
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 |
|---|---|---|---|
| CERT C Secure Coding | ARR30-C | Do not form or use out-of-bounds pointers or array subscripts | CWE More Specific |