CVE-2020-37284 in Sickbeard
Summary
by MITRE • 10/22/2026
Sickbeard through build-507 contains a reflected cross-site scripting vulnerability that allows unauthenticated attackers to inject scripts through the pattern parameter of /config/postProcessing/testNaming. Attackers can craft GET requests with malicious SVG onload payloads that the testNaming handler returns unescaped, executing JavaScript in victims' browsers. Exploitation evidence was first observed by the Shadowserver Foundation on 2023-10-22.
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Analysis
by VulDB Data Team • 10/22/2026
Sickbeard through build-507 is susceptible to a reflected cross-site scripting vulnerability within its post-processing configuration interface, specifically targeting the pattern parameter of the /config/postProcessing/testNaming endpoint. This flaw arises from an insufficient sanitization mechanism that fails to properly validate or escape user-supplied input before including it in the HTTP response generated by the test naming handler. The application processes GET requests containing malicious payloads and reflects them back into the browser context without adequate protection, allowing unauthenticated attackers to inject executable scripts directly into the victim's session environment.
The technical nature of this vulnerability aligns with CWE-79, which classifies improper neutralization of input during web page generation as a critical security weakness. Attackers can exploit this flaw by crafting specially formatted GET requests that embed malicious SVG elements equipped with onload event handlers. When an administrator or authorized user interacts with the application and triggers the test naming functionality while their session is active, the browser parses the reflected payload and executes the embedded JavaScript code within the context of the Sickbeard web interface. This execution occurs without any additional authentication checks at the point of injection, leveraging the trust relationship between the victim's browser and the vulnerable server.
The operational impact of this vulnerability extends beyond simple script execution to potential account compromise and data exfiltration. By executing arbitrary JavaScript in the context of the application, an attacker can bypass same-origin policy restrictions to steal sensitive session cookies, authentication tokens, or other confidential information stored locally by the web application. Furthermore, the malicious scripts could perform actions on behalf of the victim, such as modifying configuration settings, triggering unauthorized media processing tasks, or redirecting users to phishing sites designed to capture further credentials. The ability for unauthenticated actors to initiate these attacks means that no prior login is required to exploit this weakness, significantly lowering the barrier to entry for potential adversaries and increasing the likelihood of successful exploitation in environments where administrative access might be exposed via search engines or direct links.
Evidence of active exploitation has been documented by security researchers at the Shadowserver Foundation starting on October 22, 2023, indicating that this vulnerability is being actively targeted in the wild. This real-world exploitation activity underscores the urgency for immediate remediation efforts within affected deployments. The attack vector corresponds to ATT&CK technique T1189 Drive-by Client Side Execution, where attackers use compromised or malicious websites and web applications to exploit vulnerabilities in client-side software components like browsers. In this specific case, the Sickbeard application itself serves as the vehicle for delivering the malicious payload directly to the victim's browser through a reflected XSS mechanism rather than requiring external redirection from an unrelated site.
Mitigation strategies should focus on both immediate patching and long-term security hardening practices. The primary remediation step is to upgrade Sickbeard to a version later than build-507, where this input validation flaw has presumably been addressed by the development team through proper output encoding or context-aware escaping of user-supplied data in the testNaming response handler. In addition to upgrading software, administrators should implement web application firewalls that can detect and block common XSS patterns such as SVG onload events before they reach the vulnerable endpoint. Network segmentation and strict access controls for administrative interfaces are also recommended to limit exposure to unauthenticated users. Regular security audits and code reviews focusing on input validation logic will help prevent similar vulnerabilities from being introduced in future updates, ensuring a more robust defense against client-side injection attacks.