CVE-2026-10821 Yoast SEO Premium < 27.6.1 - Author+ Arbitrary .htaccess Directive Injection to RCE
Authors can inject Apache directives into .htaccess to achieve remote code execution via chained media uploads in Yoast SEO Premium.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-10821?
CVE-2026-10821 is a medium-severity code injection vulnerability in Unknown Yoast SEO Premium, published on 2 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official 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.
Weakness: CWE-74
Which versions are affected by CVE-2026-10821?
How do I fix CVE-2026-10821?
No fix has been published for CVE-2026-10821 yet. Limit exposure of the affected software until one is available.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-10821 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-10821 exists.
Sources
Also known as GHSA-2r8j-r49x-m28r.