CVE-2026-10821
6.6 · MEDIUMThe 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 redir…
Overview
CVE-2026-10821 is a medium-severity vulnerability. It was published on September 2, 2026 and has a CVSS 3.1 base score of 6.6 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 6.6, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
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Frequently asked questions
What is CVE-2026-10821?
CVE-2026-10821 is a medium-severity vulnerability. It was published on September 2, 2026 and has a CVSS 3.1 base score of 6.6 (MEDIUM).
How severe is CVE-2026-10821?
This vulnerability has a CVSS 3.1 base score of 6.6, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2026-10821?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-10821?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-10821 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.
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