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HIGH severity

CVE-2026-120739 — WordPress

HIGH

CVE-2026-120739 is a high-severity (CVSS 7.2) Cross-site Scripting (XSS) vulnerability. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

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)'…

Published
Updated
Affected
—
Patched
—
Exploits
None indexed
Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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.

Detection & mitigation playbook

Vulnerability

  1. Detect

    Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

  2. Remediation status

    The records we use list no fixed release for CVE-2026-120739. Check the upstream advisory for a patched version, and apply the exposure-reduction steps below in the meantime.

  3. Mitigate without a patch

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

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 insi
O3 Security · Impact-Aware SCA

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