CVE-2026-76562 in Sidebar Manager Light Plugin
Summary
by MITRE • 09/10/2026
The Sidebar Manager Light plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'sbm_description' parameter in all versions up to, and including, 1.18 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.
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Analysis
by VulDB Data Team • 09/10/2026
The Sidebar Manager Light plugin for WordPress contains a critical security vulnerability affecting all versions up to and including 1.18, characterized by insufficient input sanitization and output escaping mechanisms within the sbm_description parameter. This flaw allows unauthenticated attackers to inject arbitrary web scripts into pages managed or displayed by the plugin. The core technical issue stems from the application's failure to properly validate user-supplied data before storing it in the database and its subsequent failure to escape this data when rendering it back to the client browser. Consequently, malicious JavaScript code can be persisted within the site's content structure without requiring any form of authentication or administrative privileges, significantly lowering the barrier for exploitation compared to vulnerabilities that require higher privilege levels.
From a technical perspective, this vulnerability is classified as Stored Cross-Site Scripting, also known as Persistent XSS. Unlike reflected XSS where malicious scripts are executed immediately upon request, stored variants persist on the target server, typically in a database or file system. When an administrator or any other user with access to the affected page loads it into their browser, the injected script executes within the context of that site's domain. This execution environment grants the attacker significant leverage, as they can potentially access cookies, session tokens, and other sensitive data protected by same-origin policy restrictions if those protections are not adequately implemented or bypassed. The lack of sanitization on input means that special characters such as angle brackets and quotes are passed through directly to the output layer without transformation into safe HTML entities, enabling the browser interpreter to treat injected content as executable code rather than plain text data.
The operational impact of this vulnerability is severe due to its unauthenticated nature and persistent storage mechanism. Attackers can compromise user sessions by stealing authentication cookies, leading to unauthorized access to administrative accounts or other privileged areas of the WordPress installation. Furthermore, attackers may redirect users to malicious sites designed for phishing attacks, capture keystrokes to steal credentials entered on the page, or deface the website's appearance. Because the payload is stored server-side, every user who views the compromised content becomes a potential victim, amplifying the scope of damage far beyond what would be possible with non-persistent vulnerabilities. This can lead to significant reputational damage for site owners and potential data breaches involving sensitive information belonging to visitors or administrators.
In terms of industry standards, this vulnerability aligns closely with CWE-79: Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. Specifically, it represents a failure in both input validation (CWE-20) and output encoding (CWE-116). From an offensive security framework perspective, the exploitation technique maps to MITRE ATT&CK techniques related to Client-Side Injection and potentially Account Manipulation if used for persistence or privilege escalation. The attack vector is classified as Network-based with no required user interaction for initial injection, though it requires a victim to view the compromised page for execution, which falls under Initial Access via Spearphishing Link in some contexts depending on how the payload is delivered initially.
Mitigation strategies should focus primarily on immediate patching and robust input handling practices. Site administrators must upgrade the Sidebar Manager Light plugin to version 1.19 or later where these sanitization issues have been addressed by the developers. In addition to updating, it is crucial to implement strict Content Security Policy headers that restrict script execution sources, thereby mitigating the impact of any successful XSS injection even if input validation fails temporarily. Developers should adopt a defense-in-depth approach by ensuring all user inputs are sanitized against known malicious patterns before database storage and strictly escaped using context-aware encoding functions when outputting data to HTML contexts. Regular security audits and code reviews focusing on data flow from entry points to display layers can help identify similar weaknesses in other plugins or custom themes, reducing the overall attack surface of the WordPress environment.