CVE-2026-120739
Deferred Deferred - Pending Action

Stored XSS in Optimole WordPress Plugin via Missing Input Sanitization

Publication date: 2026-11-07

Last updated on: 2026-11-07

Assigner: Wordfence

Description
The Optimole – Optimize Images | Convert WebP & AVIF | CDN & Lazy Load | Image Optimization plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 's (missing_srcsets[*][*].s)' parameter in all versions up to, and including, 4.2.18 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The HMAC signature required to pass the REST endpoint's authorization check is published in plaintext to unauthenticated visitors inside the inline optimoleDataOptimizer JavaScript object on any page with an incomplete profile, making the effective authentication barrier nonexistent.

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Meta Information

Published
2026-11-07
Last Modified
2026-11-07
Generated
2026-11-07
AI Q&A
2026-11-07
EPSS Evaluated
N/A
NVD
CVE-2026-120739
EUVD
EUVD-2026-118600

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
optimole Optimole – Optimize Images | Convert WebP & AVIF | CDN & Lazy Load | Image Optimization From 0 (inc) to 4.2.18 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

The Optimole WordPress plugin has a stored cross-site scripting (XSS) vulnerability due to insufficient input sanitization and output escaping in the 's' parameter. Unauthenticated attackers can inject malicious scripts into pages, which execute when users access those pages. The plugin also exposes an HMAC signature in plaintext, bypassing authentication checks.

Detection Guidance

Check for the presence of the Optimole plugin in WordPress installations up to version 4.2.18. Inspect JavaScript output for the inline optimoleDataOptimizer object on pages with incomplete profiles to see if the HMAC signature is exposed in plaintext.

Impact Analysis

Attackers could steal user sessions, redirect users to malicious sites, or perform actions on their behalf. Websites using the vulnerable plugin versions may have their pages compromised, leading to data theft or defacement.

Compliance Impact

This vulnerability could lead to unauthorized data access or modification, violating GDPR (data protection) and HIPAA (health data privacy) requirements. Organizations may face compliance penalties if user data is compromised through this flaw.

Mitigation Strategies

Update the Optimole plugin to the latest version beyond 4.2.18. Remove or disable the plugin if updates are unavailable. Review and sanitize input/output handling in WordPress configurations to prevent XSS attacks.

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