Race Condition in GNU Sed

When sed is invoked with both -i (in-place edit) and --follow-symlinks, the function open_next_file() performs two separate, non-atomic filesystem operations on the same path: 1. resolves symlink to its target and stores the resolved path for determining when output is written, 2. opens the original symlink path (not the resolved one) to read the file. Between these two calls there is a race window. If an attacker atomically replaces the symlink with a different target during that window, sed will: read content from the new (attacker-chosen) symlink target and write the processed result to the path recorded in step 1. This can lead to arbitrary file overwrite with attacker-controlled content in the context of the sed process. This issue was fixed in version 4.10.

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检查时间与使用时间(TOCTOU)的竞争条件

GNU Sed 安全漏洞

GNU Sed是美国GNU社区的一个用于文本流编辑与批量处理的命令行工具。 GNU Sed存在安全漏洞，该漏洞源于同时使用-i和--follow-symlinks选项时存在竞争条件，可能导致攻击者任意覆盖文件。

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