CVE-2026-89193 in Robin Image Optimizer Plugin
Summary
by MITRE • 09/30/2026
The Robin Image Optimizer WordPress plugin before 2.0.8 does not escape values that its bundled HTML parser re-emits into element attributes when a non-default image delivery mode is enabled, allowing unauthenticated users to submit content that is stored and later executed as Cross-Site Scripting in the browser of any user viewing an affected page, including administrators.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 09/30/2026
The Robin Image Optimizer WordPress plugin, prior to version 2.0.8, contains a critical input validation flaw within its bundled HTML parser component. This vulnerability arises specifically when non-default image delivery modes are enabled on the target site. The core technical issue is that user-supplied values processed by this internal parser are not properly escaped before being re-emitted into HTML element attributes. In standard web application security practices, any data originating from untrusted sources must be strictly validated and encoded to prevent it from being interpreted as executable code by the browser's rendering engine. The failure to apply appropriate output encoding allows malicious scripts embedded within image metadata or related user inputs to persist in the DOM structure without sanitization.
This lack of proper escaping directly facilitates a Stored Cross-Site Scripting attack vector, commonly categorized under CWE-79: Improper Neutralization of Input During Web Page Generation. Because the vulnerable code path is triggered by content that has been submitted and stored on the server, the malicious payload becomes part of the page's static or dynamic content. When any user visits a webpage containing this compromised image data, their browser parses the HTML attribute containing the injected script. The browser then executes this script in the context of the victim's session, effectively bypassing same-origin policy restrictions and allowing the attacker to interact with the application as if they were the legitimate user viewing the page.
The operational impact of this vulnerability is severe due to its unauthenticated nature and broad scope. Since no authentication is required to trigger the initial storage of the malicious payload via image upload or metadata manipulation, any internet user can exploit it. Furthermore, because the script executes in the context of every visitor who views an affected page, including site administrators with elevated privileges, the potential for damage extends beyond simple defacement. Attackers can steal administrative session cookies, perform actions on behalf of admins such as creating new users or modifying settings, and exfiltrate sensitive data from the WordPress dashboard to external servers controlled by the attacker. This represents a significant compromise of both confidentiality and integrity within the affected web application environment.
Mitigation strategies for this vulnerability focus primarily on immediate software updates and defensive configuration changes. The most effective remediation is to upgrade the Robin Image Optimizer plugin to version 2.0.8 or later, where the developers have implemented proper input sanitization and output encoding mechanisms within the HTML parser logic. For organizations unable to update immediately due to compatibility constraints, disabling non-default image delivery modes can serve as a temporary workaround if those specific features are not critical to operations. Additionally, implementing a Web Application Firewall with robust Cross-Site Scripting detection rules may help block exploitation attempts by filtering out malicious payloads in HTTP requests before they reach the vulnerable parser logic. Regular security audits and code reviews focusing on output encoding practices for all user-controlled data entering HTML attributes are recommended to prevent similar flaws in future development cycles.