Is CVE-2026-10821 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-10821?

CVE-2026-10821 has a CVSS v3 severity of MEDIUM (6.6).

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CVE-2026-10821

Description

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.