CVE-2021-29271 in remark42
Summary
by MITRE • 03/28/2021
remark42 before 1.6.1 allows XSS, as demonstrated by "Locator: Locator{URL:" followed by an XSS payload. This is related to backend/app/store/comment.go and backend/app/store/service/service.go.
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Analysis
by VulDB Data Team • 04/06/2021
The vulnerability identified as CVE-2021-29271 represents a cross-site scripting flaw in the remark42 commenting system version 1.6.1 and earlier. This security issue stems from inadequate input validation and sanitization within the backend components responsible for handling comment storage and retrieval operations. The vulnerability specifically manifests when the system processes locator parameters containing URL references, creating an attack vector that allows malicious actors to inject and execute arbitrary JavaScript code within the context of other users' browsers.
The technical implementation of this vulnerability resides in the backend/app/store/comment.go and backend/app/store/service/service.go files, which handle the storage and service operations for comment data. These components fail to properly sanitize user-supplied input when processing locator parameters that contain URL information. The flaw enables attackers to craft malicious payloads by inserting an XSS payload within the locator URL field, specifically following the pattern "Locator: Locator{URL:" followed by the malicious code. This design flaw allows the system to store and subsequently render the malicious content without proper sanitization, creating a persistent XSS vulnerability that affects all users interacting with the compromised comment system.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the capability to hijack user sessions, steal sensitive information, manipulate the application's functionality, and potentially escalate privileges within the system. The vulnerability affects any user who interacts with comments containing malicious locator URLs, making it particularly dangerous in environments where user-generated content is prevalent. Attackers can leverage this vulnerability to perform session hijacking, deface web pages, redirect users to malicious sites, or execute other malicious activities that compromise the integrity and security of the entire remark42 deployment.
This vulnerability aligns with CWE-79 Cross-site Scripting, which classifies the issue as a failure to sanitize user input properly before rendering it in web pages. From an ATT&CK framework perspective, this represents a technique that enables initial access and privilege escalation through web-based attacks, specifically falling under T1566.001 Initial Access: Phishing via Email and T1071.001 Application Layer Protocol: Web Protocols. The vulnerability demonstrates poor input validation practices and inadequate security controls in the backend data handling processes, which are critical components in maintaining web application security. Organizations utilizing remark42 should immediately upgrade to version 1.6.1 or later to remediate this vulnerability, while also implementing additional security measures such as content security policies, input sanitization, and regular security audits of web applications to prevent similar issues from occurring in other components of their systems.