CVE-2026-81285

Smush – Image Optimization, Compression, Lazy Load, WebP & CDN <= 4.2.0 - Unauthenticated Denial of Service

2026-08-27 00:00

Strategic Overview

Status: Patched in 4.3.0
Affected Plugin: Smush – Image Optimization, Compression, Lazy Load, WebP & CDN
Affected Version: <= 4.2.0
CVSS: 7.5High
Weakness type: CWE-400 · Uncontrolled Resource Consumption
CVE: CVE-2026-81285

View all Smush – Image Optimization, Compression, Lazy Load, WebP & CDN vulnerabilities

At a glance

CVE-2026-81285 is a high-severity Uncontrolled Resource Consumption vulnerability in the Smush WordPress plugin, affecting versions <= 4.2.0. It carries a CVSS score of 7.5 (reachable over the network; low attack complexity; high availability impact). Exploitation requires no authentication. The issue is fixed in version 4.3.0; sites on affected versions should update now. Disclosed August 2026, reported by Asim Alshaya.

Vulnerability Overview

The Smush – Image Optimization, Compression, Lazy Load, WebP & CDN plugin for WordPress is vulnerable to Denial of Service in all versions up to, and including, 4.2.0. This is due to insufficient validation of user supplied input. This makes it possible for unauthenticated attackers to make the affected site unavailable.

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 privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on availability.

CWE-400: Uncontrolled Resource Consumption

Reaching this weakness in Smush <= 4.2.0 takes no account at all. Uncontrolled resource consumption means a request can make the server do an amount of work it never bounds, because the size or repetition of the job is taken from the request rather than capped by the code.

A single caller can hold PHP workers, database connections or disk open long enough to slow the site for everyone, without needing any account or any other flaw. For Smush the fix is 4.3.0: builds <= 4.2.0 are affected, anything from 4.3.0 onward is not.

Remediation

Update to version 4.3.0, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Smush 4.3.0 closes this, and updating the plugin is the step that ends it.

Firewall
Login Security
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-81285 https://www.wordfence.com/threat-intel/vulnerabilities/id/a7e6acce-ba76-488d-8dde-5b5895c30872 https://nvd.nist.gov/vuln/detail/CVE-2026-81285

Related records

Other vulnerabilities in Smush – Image Optimization, Compression, Lazy Load, WebP & CDN

CVSS Vector

7.5

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

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityNone
IntegrityNone
AvailabilityHigh

This record contains material that is subject to copyright

CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE®). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy.

https://www.cve.org/Legal/TermsOfUse

Defiant hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute this software vulnerability information. Any copy of the software vulnerability information you make for such purposes is authorized provided that you include a hyperlink to this vulnerability record and reproduce Defiant's copyright designation and this license in any such copy.

https://www.wordfence.com/wordfence-intelligence-terms-and-conditions/