CVE-2026-105057 in Zero Spam Plugin
Summary
by MITRE • 10/06/2026
Unauthenticated Bypass Vulnerability in Zero Spam <= 5.7.11 versions.
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Analysis
by VulDB Data Team • 10/06/2026
The vulnerability identified within Zero Spam plugin versions up to and including 5.7.11 represents a critical security flaw that allows unauthenticated attackers to bypass intended access controls or functional restrictions. This type of issue typically stems from insufficient validation of user input or improper enforcement of authentication checks on specific endpoints, API calls, or administrative functions exposed by the application. In many cases involving WordPress plugins like Zero Spam, such vulnerabilities may manifest through poorly secured AJAX handlers, REST API endpoints, or direct file access mechanisms that fail to verify whether the requesting entity possesses valid credentials or appropriate privileges before executing sensitive operations. The absence of these checks enables malicious actors to interact with system components without logging in, potentially leading to unauthorized data exposure, configuration tampering, or further exploitation chains depending on the specific functionality affected by the bypass.
From a technical perspective, this flaw aligns closely with CWE-287, which describes Improper Authentication, and often overlaps with CWE-306 for Missing Authentication for Critical Function. The root cause generally involves developers relying solely on client-side validation or assuming that certain paths are inherently protected without implementing server-side verification of session tokens, nonce values, or capability checks. When an attacker exploits this weakness, they can manipulate parameters to trigger actions such as modifying spam filtering rules, accessing user data, or executing administrative tasks remotely. This undermines the core purpose of the plugin, which is designed to protect websites from malicious submissions and automated abuse, thereby creating a paradox where the security tool itself becomes a vector for compromise if left unpatched.
The operational impact of this vulnerability can be severe, particularly in environments handling sensitive user information or high-traffic public-facing sites. Attackers may leverage the bypass to disable anti-spam protections, allowing increased volumes of malicious content such as phishing links, malware distribution URLs, or spam comments that degrade site performance and reputation. In more advanced scenarios, if the vulnerable function interacts with database queries without proper sanitization following the authentication bypass, it could lead to SQL injection attacks resulting in full database compromise. Additionally, depending on how the plugin integrates with other system components, this flaw might facilitate privilege escalation where a low-privileged user gains administrative capabilities or allows remote code execution through subsequent exploitation steps involving file uploads or command injection vectors embedded within manipulated inputs.
Mitigation strategies must prioritize immediate remediation by updating to patched versions of Zero Spam that address these authentication gaps. Administrators should ensure their WordPress installations are fully updated, including core software and all active plugins, as vendors frequently release patches alongside security advisories for related components. Until an update is applied, temporary mitigations may include restricting access to administrative areas via IP whitelisting or Web Application Firewall rules that block suspicious request patterns associated with exploitation attempts. It is also advisable to audit plugin configurations for any exposed endpoints and disable unnecessary features if they are not required by the site’s operational model. Regular security audits using static analysis tools can help identify similar coding practices across other plugins, ensuring a more robust defense-in-depth posture against unauthenticated access vulnerabilities in future deployments.