CVE-2026-16957

Deferred Deferred - Pending Action

Slim SEO WordPress Plugin Post Meta Exposure Vulnerability

Publication date: 2026-08-09

Last updated on: 2026-08-26

Assigner: WPScan

Description

The Slim SEO WordPress plugin before 4.9.11 does not restrict a post-meta preview feature to posts the user is allowed to edit, verifying only read access, allowing users with the Contributor role to read arbitrary post meta, including protected and private keys, of published posts they do not own, including password-protected posts and posts of non-public post types.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-08-09

Last Modified

2026-08-26

Generated

2026-08-29

AI Q&A

2026-08-09

EPSS Evaluated

2026-08-28

NVD

CVE-2026-16957

EUVD

EUVD-2026-54888

Affected Vendors & Products

Vendor	Product	Version / Range
wpseo	slim_seo	to 4.9.11 (exc)
slim_seo	slim_seo	to 4.9.11 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-639	The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.

Attack-Flow Graph

Executive Summary

This vulnerability in the Slim SEO WordPress plugin before version 4.9.11 allows users with the Contributor role to read arbitrary post meta data, including protected and private keys, of published posts they do not own. The issue is due to improper access control, specifically an Insecure Direct Object Reference (IDOR) flaw.

Detection Guidance

To detect this vulnerability, check the Slim SEO plugin version installed on your WordPress site. If it is below 4.9.11, the site is vulnerable. You can verify the version via the WordPress admin dashboard under Plugins or by inspecting the plugin files directly.

Impact Analysis

An attacker with Contributor access could read sensitive data like passwords, private keys, or other protected meta information from posts they do not own. This includes password-protected posts and non-public post types, potentially leading to data leaks or further exploits.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating compliance requirements under GDPR (data protection) and HIPAA (health information privacy). Organizations using the vulnerable plugin may face legal penalties or reputational damage.

Mitigation Strategies

Immediately update the Slim SEO plugin to version 4.9.11 or later. This can be done through the WordPress admin dashboard under Plugins. If automatic updates are disabled, manually download and install the latest version from the official WordPress plugin repository.

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