CVE-2022-1820 in Keep Backup Daily Plugin
Summary
by MITRE • 06/13/2022
The Keep Backup Daily plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the ‘t’ parameter in versions up to, and including, 2.0.2 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.
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Analysis
by VulDB Data Team • 04/08/2026
The Keep Backup Daily plugin for WordPress represents a critical security vulnerability classified as CVE-2022-1820, which manifests as a reflected cross-site scripting flaw in versions up to and including 202. The vulnerability specifically targets the 't' parameter within the plugin's functionality, creating an attack vector that allows malicious actors to inject arbitrary web scripts into web pages. This weakness exists due to inadequate input sanitization measures and insufficient output escaping mechanisms that should normally protect against such attacks. The flaw affects unauthenticated attackers who can exploit this vulnerability without requiring any prior login credentials or privileged access to the WordPress installation. The reflected nature of this XSS vulnerability means that the malicious script is reflected off the web server and executed in the victim's browser, making it particularly dangerous as it can be delivered through various attack vectors including malicious links or email attachments. This vulnerability directly maps to CWE-79 which defines Cross-Site Scripting as a common web application security flaw where untrusted data is incorporated into web pages without proper validation or escaping. The operational impact of this vulnerability extends beyond simple script injection, as it provides attackers with the capability to perform session hijacking, steal user credentials, redirect users to malicious websites, or even execute more sophisticated attacks such as defacement of the WordPress site. The attack requires social engineering elements where users must be tricked into clicking on malicious links that contain the crafted payload, but once executed, the consequences can be severe for both the website administrators and end users. According to ATT&CK framework, this vulnerability aligns with T1203 - Exploitation for Client Execution, where adversaries leverage client-side exploits to execute malicious code in the context of the user's browser. The vulnerability's severity is compounded by the fact that it affects a backup plugin, which typically handles sensitive data and system configurations, making the potential impact on data integrity and confidentiality significantly higher. WordPress plugin security is particularly critical because these extensions often have elevated privileges and access to core system functions, making them attractive targets for attackers seeking to escalate their privileges or gain unauthorized access to the entire WordPress installation. The lack of proper input validation in the 't' parameter allows attackers to inject malicious JavaScript code that gets executed when the page is rendered, potentially leading to complete compromise of user sessions and unauthorized access to the WordPress administrative interface.
The technical exploitation of CVE-2022-1820 requires understanding how the plugin processes user input and handles output rendering. When the 't' parameter is passed to the plugin's code, the insufficient sanitization means that any malicious input containing script tags or other executable code is not properly filtered or escaped before being included in the HTTP response. This creates a situation where the web server returns the attacker's malicious input as part of the normal page content, which is then executed by the victim's browser. The vulnerability demonstrates poor security practices in input handling, where the plugin fails to implement proper sanitization routines that should validate and sanitize all user-provided data before it is processed or rendered. The output escaping mechanism that should normally prevent script execution is either missing or inadequate, allowing the malicious payload to persist in the response and be executed by the browser. Security experts categorize this type of vulnerability under the OWASP Top Ten as part of the A03:2021 - Injection category, which includes XSS vulnerabilities that occur when applications fail to properly escape or validate user input. The vulnerability's impact is amplified because backup plugins typically operate with elevated privileges and may have access to sensitive system information, database credentials, or backup files that could be leveraged by attackers to cause further damage. The reflected nature of the attack means that the malicious payload must be crafted specifically for each victim and delivered through carefully constructed URLs, but this also makes it difficult to detect and prevent through traditional security measures.
Mitigation strategies for CVE-2022-1820 should focus on immediate remediation actions including upgrading to the latest version of the Keep Backup Daily plugin where the vulnerability has been patched. Administrators should also implement input validation at multiple levels including server-side validation, proper output escaping for all dynamic content, and content security policy headers to prevent unauthorized script execution. The WordPress core security team recommends that all plugin developers follow secure coding practices including input sanitization, output escaping, and proper validation of all user-provided data. Organizations should also consider implementing web application firewalls that can detect and block suspicious input patterns, though these should not be considered a complete solution. Regular security audits and penetration testing of WordPress installations can help identify similar vulnerabilities in other plugins or themes that may not have been patched. The vulnerability highlights the importance of keeping all WordPress components updated and following security best practices such as implementing the principle of least privilege, monitoring for unusual activity, and maintaining regular backups of the WordPress installation. From a defensive perspective, the implementation of CSP headers can provide additional protection against XSS attacks by restricting which scripts can be executed on the page, even if an attacker manages to inject malicious code. Security monitoring should include detection of unusual parameter values in HTTP requests, particularly those that might contain script tags or other suspicious content that could indicate an attempted XSS attack. The vulnerability also underscores the need for comprehensive security training for WordPress administrators and developers to understand the importance of proper input validation and output escaping in preventing common web application vulnerabilities.