CVE-2026-66619 in Newsletters Plugin
Summary
by MITRE • 09/17/2026
Administrator SQL Injection in Newsletters <= 4.18 versions.
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Analysis
by VulDB Data Team • 09/17/2026
The vulnerability identified as an administrator-level SQL injection within the WordPress plugin Newsletters prior to version 4.19 represents a critical security flaw that compromises the integrity of the underlying database and potentially the entire web application infrastructure. This specific weakness arises from insufficient input validation and sanitization mechanisms when processing user-supplied data in administrative endpoints associated with newsletter management functions. Unlike standard SQL injection vulnerabilities that may be exploitable by unauthenticated users or low-privilege accounts, this particular instance requires authentication as an administrator, which significantly narrows the attack vector but does not diminish its severity due to the high level of access granted to such roles. The flaw typically manifests when specific parameters related to newsletter configuration, subscriber lists, or campaign settings are passed directly into SQL queries without proper escaping using prepared statements or parameterized queries. This allows an attacker who has obtained administrative credentials through phishing, credential stuffing, or other means to inject malicious SQL code that alters the logic of database operations.
From a technical perspective, this vulnerability aligns with CWE-89 Improper Neutralization of Special Elements used in an SQL Command, which is consistently ranked among the most dangerous software weaknesses due to its potential for data exfiltration and remote code execution via out-of-band techniques or stacked queries depending on the database engine configuration. The operational impact of exploiting this flaw extends far beyond simple data theft; it enables full control over the WordPress installation's backend logic. An attacker can manipulate existing records, insert malicious entries into subscriber tables to facilitate spam campaigns, or delete critical configuration data that disrupts service availability. Furthermore, if the underlying MySQL server is configured with certain privileges such as FILE access, an authenticated administrator could potentially write files to arbitrary locations on the web server filesystem, leading to complete system compromise and remote code execution. This transforms a database-level injection into a full-scale infrastructure breach where sensitive user data including email addresses and personal information contained within newsletter subscriptions are exposed to unauthorized parties in violation of privacy regulations such as GDPR or CCPA.
The exploitation path for this vulnerability is closely mapped to the MITRE ATT&CK framework, specifically under techniques related to SQL Injection (T1190) and potentially Data from Local System (T1005) if data exfiltration occurs. The initial access phase relies on valid administrative credentials, placing it within the Initial Access or Persistence tactics depending on whether the attacker uses the injection for immediate gain or establishes a backdoor through database triggers or stored procedures. Once inside, the lateral movement is limited to the scope of the web application and its connected databases unless further vulnerabilities exist in adjacent systems. The lack of proper input sanitization indicates a fundamental gap in secure coding practices during the development phase, suggesting that security testing such as static analysis or dynamic penetration testing was either absent or failed to identify these specific administrative endpoints.
Mitigation strategies must prioritize immediate patching by upgrading the Newsletters plugin to version 4.19 or later where this issue has been resolved through rigorous input validation and the implementation of parameterized queries for all database interactions involving user-supplied data. In environments where immediate updating is not feasible, temporary mitigations should include restricting administrative access via IP whitelisting using web application firewalls or network segmentation to limit exposure to trusted sources only. Additionally, implementing strict Content Security Policy headers and ensuring that the database account used by WordPress operates with minimal privileges can reduce the blast radius of any successful exploitation attempt. Regular security audits focusing on SQL injection patterns in all administrative interfaces are essential to prevent recurrence, alongside enforcing strong password policies and multi-factor authentication for administrator accounts to mitigate the risk of credential compromise which serves as the prerequisite vector for this specific vulnerability.