CVE-2026-16957

Slim SEO <= 4.9.10 - Insecure Direct Object Reference to Authenticated (Contributor+) Arbitrary Post Meta Disclosure

2026-08-03 00:00
Shivamani Vastrala

Strategic Overview

Status
Patched in 4.9.11
Affected Plugin
Slim SEO – AI SEO Plugin, Lightweight, Fast & Automated
Affected Version
<= 4.9.10
CVSS
4.3Medium
Weakness type
CWE-639 · Authorization Bypass Through User-Controlled Key
CVE
CVE-2026-16957
View all Slim SEO – AI SEO Plugin, Lightweight, Fast & Automated vulnerabilities

At a glance

CVE-2026-16957 is a medium-severity Authorization Bypass Through User-Controlled Key vulnerability in the Slim SEO WordPress plugin, affecting versions <= 4.9.10. It carries a CVSS score of 4.3 (reachable over the network; low attack complexity). Exploitation requires an authenticated account at Contributor level or above. The issue is fixed in version 4.9.11; sites on affected versions should update now. Disclosed August 2026, reported by Shivamani Vastrala.

Vulnerability Overview

The Slim SEO plugin for WordPress is vulnerable to Insecure Direct Object Reference in versions up to, and including, 4.9.10. This is due to insufficient capability check in the can_edit_post() REST API permission callback using edit_posts and read_post instead of the post-specific edit_post capability. This makes it possible for authenticated attackers, with contributor-level access and above, to read arbitrary post meta for posts they do not have permission to edit.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user.

CWE-639: Authorization Bypass Through User-Controlled Key

Slim SEO <= 4.9.10 carries this weakness at can_edit_post(), and reaching it takes an account at Contributor level or above. Authorization bypass through a user-controlled key, often called insecure direct object reference, means the application looks up a record by an identifier from the request without checking that the caller owns it.

Changing a number in the request is enough to read or modify other users' records, which on commerce and membership sites means customer data. For Slim SEO the fix is 4.9.11: builds <= 4.9.10 are affected, anything from 4.9.11 onward is not.

Remediation

Update to version 4.9.11, or a newer patched version

How does WordSec protect against this?

Because it turns on account access, WordSec's login security is the relevant layer: role-based two-factor, captcha and brute-force limits raise the cost of getting the account this needs. None of that substitutes for the fix: Slim SEO 4.9.11 closes this, and updating the plugin is the step that ends it.

  • Login Security
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-16957https://www.wordfence.com/threat-intel/vulnerabilities/id/01ec3ba3-4627-4072-b15d-44e98c652836https://nvd.nist.gov/vuln/detail/CVE-2026-16957

Related records

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