CVE-2026-10821 — MEDIUM (6.6)

Vulnerability 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.

CVSS Score

6.6

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

HIGH

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

HIGH

Integrity

HIGH

Availability

HIGH

Related Weaknesses (CWE)

CWE-74

References

FAQ

What is CVE-2026-10821?

CVE-2026-10821 is a vulnerability with a CVSS score of 6.6 (MEDIUM). 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...

How severe is CVE-2026-10821?

CVE-2026-10821 has been rated MEDIUM with a CVSS base score of 6.6/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-10821?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.