CVE-2026-129141 in paicoding
Summary
by MITRE • 11/13/2026
paicoding 1.0.0 through 1.0.3 contains a stored cross-site scripting vulnerability because SeoInjectService embeds user profile text without escaping in an inline JSON-LD script element. Authenticated attackers can add a closing script tag followed by HTML to their profile, executing scripts for visitors of their profile page and stealing the non-HttpOnly f-session cookie.
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Analysis
by VulDB Data Team • 11/13/2026
The vulnerability identified in paicoding versions 1.0.0 through 1.0.3 represents a critical security flaw rooted in improper input validation and output encoding within the application's user profile management system. Specifically, the SeoInjectService component is responsible for embedding user-provided text into inline JSON-LD script elements to facilitate search engine optimization metadata injection. However, this service fails to properly sanitize or escape special characters present in the user profile data before insertion into the Document Object Model. This lack of encoding allows an attacker to inject malicious payloads directly into the rendered HTML structure by manipulating their own profile information. The core technical failure lies in the absence of context-aware output encoding, which is a fundamental requirement when injecting dynamic content into script blocks or JSON structures embedded within HTML pages.
From a classification perspective, this vulnerability aligns with CWE-79, commonly known as Stored Cross-Site Scripting (XSS). Unlike reflected XSS where malicious scripts are executed immediately via a crafted URL, stored XSS involves the persistence of the attack vector on the target server. In this case, the injected script is saved to the database and subsequently served to other users when they visit the compromised profile page. This distinction significantly increases the severity of the vulnerability because it does not require social engineering tricks such as phishing links; instead, any authenticated user who views the attacker's profile will automatically trigger the malicious code execution in their browser context. The presence of this flaw indicates a systemic issue in how the application handles untrusted data across its service layer, particularly within components designed for SEO integration that may have lower security scrutiny than core authentication modules.
The operational impact of this vulnerability is severe due to the specific mechanism used by the attacker and the nature of the session management employed by paicoding. By injecting a closing script tag followed by additional HTML or JavaScript code into their profile, an authenticated attacker can break out of the intended JSON-LD context and execute arbitrary scripts within the victim's browser environment. The primary objective in this scenario is credential theft, specifically targeting non-HttpOnly session cookies. Because these cookies are accessible via client-side scripting APIs such as document.cookie, the malicious script can read the f-session cookie value and exfiltrate it to a remote server controlled by the attacker. This effectively allows the attacker to hijack the victim's active session without needing their password or multi-factor authentication credentials, leading to full account compromise.
This attack vector is closely mapped to MITRE ATT&CK techniques related to Client-Side Scripting Injection and Session Hijacking. The initial access phase involves leveraging stored XSS to execute code in a trusted context, which falls under the T1059 category of command and script interpretation within the browser environment. The subsequent action of reading cookies corresponds to data exfiltration over an alternative protocol or via web requests initiated by JavaScript. This capability undermines the confidentiality and integrity guarantees provided by session management systems that rely on HttpOnly flags for protection against client-side access. For applications handling sensitive user interactions, such as social networking platforms like paicoding, this vulnerability poses a direct threat to user privacy and account security, potentially enabling further attacks such as impersonation, unauthorized data modification, or lateral movement within the application's feature set if additional privileges are tied to session validity.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The most urgent fix involves implementing strict output encoding for all user-supplied content before it is embedded into HTML contexts, particularly within script blocks where standard HTML entity escaping may not be sufficient or correctly interpreted by the JSON parser. Developers should utilize context-specific encoders that understand the nuances of JavaScript string literals and JSON structures to prevent tag injection and code execution. Additionally, ensuring that session cookies are marked with the HttpOnly flag is a critical defense-in-depth measure that would have prevented this specific exploitation scenario even if the XSS vulnerability existed. This flag instructs browsers not to expose cookie values to client-side scripts, thereby neutralizing the attacker's ability to steal sessions via document.cookie access.
Beyond immediate patches, organizations should adopt secure coding practices such as Content Security Policy (CSP) implementation to restrict inline script execution and limit the domains from which resources can be loaded. Regular security code reviews focusing on data flow analysis between user input endpoints and sensitive output sinks are essential for identifying similar flaws in other components like SeoInjectService. Automated static application security testing tools configured with rules for XSS detection should also be integrated into the development pipeline to catch these issues early. By combining robust encoding standards, secure cookie configuration, and proactive monitoring, developers can effectively mitigate stored cross-site scripting risks and protect user accounts from session hijacking attacks in paicoding and similar web applications.