Description

Contributor Cross Site Scripting (XSS) in Gallery PhotoBlocks <= 1.3.4 versions.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-09-02T12:17:15.540Z",
  "pubdate": "2026-09-02T12:17:15.540Z",
  "executiveSummary": "A Cross-Site Scripting (XSS) vulnerability exists within the Gallery PhotoBlocks plugin for WordPress, specifically affecting versions 1.3.4 and below. The vulnerability stems from insufficient input sanitization of user-supplied data, allowing authenticated users with Contributor-level privileges to inject malicious scripts into the application.\nThe vulnerability poses a significant security risk, as it permits the execution of arbitrary JavaScript within the context of the victim's browser session. By leveraging this flaw, an attacker could potentially hijack administrative sessions, perform unauthorized actions on behalf of other users, or redirect victims to malicious web resources. Successful exploitation requires the attacker to possess a Contributor account, which is a common privilege level in many WordPress installations. Once the payload is stored, it triggers upon the execution of the affected plugin component, such as when an administrator views or interacts with the compromised gallery content. This vulnerability highlights the necessity of strict input validation and output encoding for all user-accessible fields, particularly in plugins that handle dynamic content rendering.",
  "technicalDetails": "The vulnerability is classified as Stored Cross-Site Scripting (XSS) occurring within the Gallery PhotoBlocks plugin. The root cause is the failure of the plugin to properly sanitize or escape input provided by users with Contributor privileges before saving it to the database. When the plugin subsequently renders this data, the browser interprets the input as executable code rather than plain text.\nThe attack flow commences when an authenticated Contributor accesses the plugin’s interface to create or modify a gallery. During the data entry process, the attacker injects a crafted payload—typically containing malicious JavaScript tags—into fields that the plugin fails to sanitize adequately. Because the plugin does not enforce strict input filtering for the Contributor role, the malicious script is stored persistently in the database.\nThe exploitation process completes when a high-privileged user, such as an Administrator, views the compromised gallery. Upon loading the page, the plugin retrieves the malicious script from the database and renders it directly into the HTML document. The victim’s browser then executes the embedded JavaScript in the context of the origin domain. This bypasses typical Same-Origin Policy (SOP) protections, allowing the attacker to interact with the victim’s session data, steal authentication tokens (such as session cookies), or initiate unauthorized requests using the victim's credentials.\nThe vulnerable component is identified within the input handling logic of Gallery PhotoBlocks <= 1.3.4. The lack of output encoding (e.g., using WordPress functions like esc_html() or esc_js()) during the rendering phase allows the injected payload to be evaluated by the Document Object Model (DOM). Since Contributors are often trusted users in collaborative WordPress environments, this flaw effectively allows for privilege escalation through the compromise of administrative sessions. The attack is restricted to the web browser and does not require additional network exposure beyond the standard HTTP/HTTPS channels used to interact with the WordPress dashboard."
}