CWE-124: Buffer Underwrite ('Buffer Underflow')
CWE版本: 4.18
更新日期: 2025-09-09
弱点描述
The product 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: 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 Confidentiality Availability Access Control Other
技术影响: Execute Unauthorized Code or Commands Modify Memory Bypass Protection Mechanism Other
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. The consequences would only be limited by how the affected data is used, such as an adjacent memory location that is used to specify whether the user has special privileges.
影响范围: Access Control Other
技术影响: Bypass Protection Mechanism Other
说明: When the consequence is arbitrary code execution, this can often be used to subvert any other security service.
潜在缓解措施
阶段: Requirements
描述: Choose a language that is not susceptible to these issues.
阶段: Implementation
描述: All calculated values that are used as index or for pointer arithmetic should be validated to ensure that they are within an expected range.
观察示例
参考: CVE-2021-24018
buffer underwrite in firmware verification routine allows code execution via a crafted firmware image
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
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 | - | UNDER - Boundary beginning violation ('buffer underflow'?) | - |
| CLASP | - | Buffer underwrite | - |
| Software Fault Patterns | SFP8 | Faulty Buffer Access | - |