CVE-2026-39795 in SendPress Newsletters Plugin
Summary
by MITRE • 10/06/2026
Unauthenticated SQL Injection in SendPress Newsletters <= 1.26.1.20 versions.
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Analysis
by VulDB Data Team • 10/06/2026
The vulnerability identified as an unauthenticated SQL injection flaw within the SendPress Newsletters plugin, affecting versions up to and including 1.26.1.20, represents a critical security deficiency in how user-supplied input is processed by the application's backend database layer. This specific class of vulnerability allows remote attackers who do not possess valid credentials or authentication tokens to interact directly with the underlying Structured Query Language (SQL) engine used by the web application. The root cause typically stems from insufficient sanitization and validation of data inputs, such as query parameters, POST body content, or HTTP headers, before they are concatenated into SQL statements for execution. In many WordPress plugin architectures, this often occurs when functions intended to retrieve or manipulate newsletter subscriber lists, campaign statistics, or configuration settings fail to properly escape special characters like single quotes or utilize parameterized queries effectively.
From a technical perspective, the exploitation of this vulnerability relies on the injection of malicious SQL syntax that alters the logic of the original database query. An attacker can craft specific payloads designed to bypass existing authentication checks or extract sensitive data from the database schema. Because the flaw is unauthenticated, it does not require any prior interaction with login forms or session management systems, making it particularly dangerous in automated scanning scenarios and widespread exploitation campaigns. The vulnerability aligns closely with CWE-89, which defines Improper Neutralization of Special Elements used in an SQL Command, commonly known as SQL Injection. This classification highlights the failure to neutralize elements that could change the intent of a command executed by the interpreter, specifically within the context of database interactions.
The operational impact of this vulnerability is severe and multifaceted. Successful exploitation can lead to unauthorized access to sensitive information stored in the WordPress database, including user credentials, email addresses, personal identifiable information associated with newsletter subscribers, and potentially administrative configuration data. Attackers may also use SQL injection techniques such as UNION-based attacks or blind boolean-based injections to enumerate database structure, extract table names, and dump entire tables of content. In more advanced scenarios, if the underlying database server permits it, an attacker might leverage this flaw to execute operating system commands through specific database features like xp_cmdshell in Microsoft SQL Server or LOAD_FILE functions in MySQL, thereby achieving full remote code execution on the hosting environment. This effectively compromises not only the web application but also the integrity and confidentiality of the entire backend infrastructure supporting the site.
This vulnerability is further contextualized by its relevance to MITRE ATT&CK techniques related to initial access and credential harvesting. Specifically, it maps to T1190 Exploit Public-Facing Application, where adversaries exploit vulnerabilities in internet-facing software to gain a foothold within a network. The lack of authentication requirement places this flaw in the highest risk category for automated exploitation tools commonly found on dark web marketplaces or as part of large-scale botnet activities targeting WordPress ecosystems. Organizations running affected versions are exposed to significant reputational damage, regulatory compliance violations such as GDPR or CCPA due to data breaches, and potential service disruption if attackers choose to delete or corrupt database records rather than exfiltrate them.
Mitigation strategies must be implemented immediately to address this critical risk. The primary remediation is to upgrade the SendPress Newsletters plugin to a version newer than 1.26.1.20 where the developers have presumably patched the input validation logic and enforced proper parameterization of database queries. If upgrading is not immediately feasible, temporary mitigations should include implementing Web Application Firewall rules that detect and block common SQL injection patterns in HTTP requests targeting the plugin's endpoints. Additionally, administrators should ensure that the principle of least privilege is applied to the database user account used by WordPress, restricting permissions so that even if an injection occurs, the attacker cannot perform destructive actions like dropping tables or accessing system-level files. Regular security audits and code reviews focusing on data handling practices are essential to prevent similar vulnerabilities in future updates or custom integrations within the application ecosystem.