CVE-2026-8622 in Image Sizes on Demand Plugin
Summary
by MITRE • 06/24/2026
The Image Sizes on Demand plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via PHP_SELF Server Variable in all versions up to, and including, 1.3 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. The injected payload only executes in the context of an administrator, as the settings page requires the manage_options capability to render.
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Analysis
by VulDB Data Team • 06/24/2026
The Image Sizes on Demand plugin for WordPress presents a critical reflected cross-site scripting vulnerability that affects all versions up to and including 1.3. This security flaw stems from inadequate input sanitization and output escaping mechanisms within the plugin's handling of the PHP_SELF server variable, creating an exploitable condition that allows attackers to inject malicious scripts into web pages. The vulnerability specifically manifests when the plugin processes user-supplied data through the PHP_SELF variable without proper validation or encoding, enabling attackers to craft malicious payloads that can be executed in the context of authenticated administrators.
The technical implementation of this vulnerability occurs at the server-side processing level where the plugin fails to properly sanitize input received through the PHP_SELF variable which is part of the HTTP_SERVER_VARS superglobal array. When an attacker crafts a malicious request containing script tags or other executable code within parameters that get processed by the vulnerable plugin, these inputs are directly reflected back to users without appropriate HTML escaping or context-aware encoding. The vulnerability requires no authentication for exploitation as attackers can craft malicious URLs and distribute them through social engineering tactics such as phishing emails or compromised websites.
The operational impact of this vulnerability is significant given that the affected settings page requires the manage_options capability to render, meaning that any successful injection will only execute within the context of an authenticated administrator's browser session. This creates a scenario where attackers can potentially escalate privileges or perform administrative actions through persistent XSS attacks, especially if administrators visit malicious pages containing the injected scripts. The reflected nature of this vulnerability means that the attack must be delivered to the victim through external means such as crafted links in emails or compromised third-party websites, making it particularly dangerous in targeted campaigns.
Mitigation strategies for this vulnerability should include immediate patching to version 1.4 or later where the sanitization issues have been addressed. Administrators should also implement additional security measures including Content Security Policy headers to prevent execution of unauthorized scripts, regular monitoring of plugin directories for suspicious modifications, and implementing web application firewalls to detect and block malicious requests. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws and maps to ATT&CK technique T1566.001 for initial access through spearphishing attachments or links, making it a critical target for both defensive security teams and red team operations seeking to identify and remediate such exposure vectors in WordPress environments.
The exploitation of this vulnerability demonstrates the importance of proper input validation and output encoding practices in web applications, particularly within content management systems where plugins often handle user-supplied data without adequate sanitization. Organizations should conduct regular security assessments of their WordPress installations to identify similar vulnerabilities in other third-party plugins that may expose their systems to similar reflected XSS attack vectors. The vulnerability also highlights the need for comprehensive security training for administrators who may inadvertently click on malicious links, as the successful exploitation requires social engineering components that target human factors within security processes rather than purely technical weaknesses.