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Yoast SEO – Advanced SEO with real-time guidance and built-in AI Plugin Vulnerability (CVE-2026-15425)

Nick Paliughi
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Security Alert Summary

The Yoast SEO – Advanced SEO with real-time guidance and built-in AI plugin for WordPress contains a stored cross-site scripting (XSS) vulnerability affecting all versions up to and including 28.0. Authenticated users with author-level access or higher can inject script into a post slug (post_name) that will execute when a user visits the injected page. The issue depends on pretty permalinks and the plugin embedding the stored percent-encoded post_name in generated permalinks.

CVE Details

  • CVE ID: CVE-2026-15425
  • Affected component: Yoast SEO – Advanced SEO with real-time guidance and built-in AI plugin for WordPress
  • Affected versions: All versions up to and including 28.0
  • Published: July 25, 2026 at 7:17:09 AM UTC
  • Last modified: July 25, 2026 at 7:17:09 AM UTC
  • CVSS v3.1: Base score 6.4, severity MEDIUM, vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
  • Authentication / privileges / user interaction: Requires authentication with low privileges (author-level and above). No user interaction required.
  • Primary impact: Confidentiality: Low; Integrity: Low; Availability: None
  • Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation – Cross-site Scripting)

Technical Details

The vulnerability is a stored cross-site scripting (XSS) issue that occurs via the post slug (post_name). Insufficient input sanitization and output escaping allow an authenticated user with author-level access or higher to store percent-encoded payloads in the post_name. When pretty permalinks are enabled, the plugin relies on get_permalink() to generate URLs that include the stored percent-encoded post_name; the embedded value can lead to script execution when pages are viewed.

The impact is limited to contexts where the stored slug is included unescaped in generated URLs or page output. The vulnerability does not require a network-exposed unauthenticated vector; it requires an attacker with an account that can create or edit posts at author level or above.

How This Could Impact Your Website

In a typical site workflow, a site owner manages administrators, internal staff operate as editors, and external contractors or contributors may have author-level access. An author with malicious intent or a compromised author account could create or update a post slug containing a crafted payload. Any user who visits the injected post could have the payload executed in their browser, potentially exposing session-scoped data or enabling targeted actions in the context of that user.

Practical consequences include limited exposure of information accessible in the browser context and an increased risk of targeted phishing or social engineering against staff who view the affected pages. The vulnerability does not imply full site takeover, but it does present real, actionable risk where author-level users are not tightly controlled. If you\’re unsure whether your site is affected or how to assess your current user roles and plugins, it may be worth having a professional review.

Recommended Actions

  • Update the affected plugin as soon as a patched version is available.
  • Review and reduce unnecessary user roles, especially author and contributor accounts.
  • Enforce strong passwords and enable two-factor authentication for editors and administrators.
  • Remove unused or unmaintained plugins.
  • Monitor site activity and logs for unusual behavior, especially changes to post slugs or unexpected post edits.

If you\’d like help reviewing your plugins, user roles, or overall WordPress security posture, our team at Freshy is happy to help.

References

Nick Paliughihttps://freshysites.com/team/nick-paliughi/
Nick was born in California and now resides in Lake Worth, FL. He has 10 years of experience building and maintaining sites in WordPress, which he is excited to put to use at Freshy. Prior to starting at Freshy in 2022 his focus was on WordPress security & malware removal. When he’s not tending to your website, Nick is installing exhibitions at art galleries and museums in Palm Beach County, and if he’s lucky surfing at the Lake Worth pier.

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