CVE-2026-11900

Ad Inserter <= 2.8.16 - Insecure Direct Object Reference to Authenticated (Contributor+) Arbitrary Post Content Disclosure via 'data' Shortcode Attribute

2026-07-02 19:01
nightward

Strategic Overview

Status
Patched in 2.8.17
Affected Version
<= 2.8.16
CVSS
4.3Medium
Weakness type
CWE-639 · Authorization Bypass Through User-Controlled Key
CVE
CVE-2026-11900
View all Ad Inserter – Ad Manager & AdSense Ads vulnerabilities

At a glance

CVE-2026-11900 is a medium-severity Authorization Bypass Through User-Controlled Key vulnerability in the Ad Inserter WordPress plugin, affecting versions <= 2.8.16. 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 2.8.17; sites on affected versions should update now. Disclosed July 2026, reported by nightward.

Vulnerability Overview

The Ad Inserter – Ad Manager & AdSense Ads plugin for WordPress is vulnerable to Insecure Direct Object Reference in versions up to and including 2.8.16 via the 'data' attribute of the [adinserter] shortcode. This is due to the replace_ai_tags() function processing a {reusable-block-N} tag pattern that calls get_post_field('post_content', N) without verifying the requesting user's capability with current_user_can('read_post'), without restricting the post type to 'wp_block', and without checking the post status. This makes it possible for authenticated attackers, with Contributor-level access and above, to read the full content of arbitrary posts including Private, Draft, Pending, Trashed, and password-protected posts owned by other users, by placing the shortcode in a post they own and previewing it.

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

Ad Inserter <= 2.8.16 carries this weakness at data, 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 Ad Inserter the fix is 2.8.17: builds <= 2.8.16 are affected, anything from 2.8.17 onward is not.

Remediation

Update to version 2.8.17, 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: Ad Inserter 2.8.17 closes this, and updating the plugin is the step that ends it.

  • Login Security
  • Alerts

External References

Related records

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