Smush – Lazy Load Images, Optimize & Compress Images <= 4.3.3 - Authenticated (Administrator+) Missing Authorization to Network-Wide Settings Modification on Multisite

ID

WPSEC-2026-0237

Plugin

Smush – Image Optimization, Compression, Lazy Load, WebP & CDN (wp-smushit)

Affected

all versions before 4.3.4

Remediation

Update to 4.3.4 or later.

CVSS 3.1

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:L

Weakness

CWE-862

Usage

Plugin High · Affected versions High among sites WPSec scans, 2026-10-22

Attack surface

Smush – Lazy Load Images, Optimize & Compress Images on WPSec AttackSurface

Fix released

2026-09-29

Published

2026-10-02

Description

The Smush plugin for WordPress is vulnerable to unauthorized modification of network-wide data in all versions up to, and including, 4.3.3 due to missing network-level capability checks on several AJAX actions. On multisite, the smush_sync_settings action accepted the 'permissions' context from any subsite administrator and wrote the network-wide subsite access controls (wp-smush-networkwide), and the legacy smush_save_settings handler did the same. The reset_settings action deleted network-wide options and reset the Smush settings of every subsite, and the wp_smush_disconnect_site action disconnected the whole network from the WPMU DEV Hub, all while checking only the manage_options capability. This makes it possible for authenticated attackers with administrator access to a single subsite to change which Smush modules subsites may control, reset Smush configuration across the network, or disconnect the network from the WPMU DEV Hub. Only multisite installations are affected.

References

• https://wpsec.com/vuln/WPSEC-2026-0237/
• https://plugins.svn.wordpress.org/wp-smushit/tags/4.3.4/
• https://wordpress.org/plugins/wp-smushit/

Published by WPSec. Provided as is, without warranty. Corrections: contact us.

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