The Yoast SEO Premium WordPress plugin before 27.6.1 does not sanitize control characters from redirect origins before writing them to the site's Apache configuration file when the file-based redirect mode is enabled, and the redirect-creation endpoint is reachable by users with only Author-level access. This allows such users to inject arbitrary newline-delimited Apache directives into the root .htaccess file. On Apache servers that honour PHP directives, the injection can be chained with the user's own media upload (a polyglot image carrying a PHP payload) and an auto_prepend_file directive to achieve Remote Code Execution.
CVSS Details
- CVSS 3.1 Base Score: 6.6
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H)
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