CVE-2004-1827 in YaBB
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in YaBB 1 Gold(SP1.3) and YaBB SE 1.5.1 Final allows remote attackers to inject arbitrary web script via the background:url property in (1) glow or (2) shadow tags.
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Analysis
by VulDB Data Team • 06/26/2025
The vulnerability identified as CVE-2004-1827 represents a critical cross-site scripting flaw affecting YaBB forums versions 1 Gold(SP1.3) and YaBB SE 1.5.1 Final. This security weakness resides in the forum software's handling of CSS properties within HTML rendering processes, specifically targeting the background:url property within glow and shadow CSS tags. The vulnerability operates at the application layer and constitutes a classic client-side attack vector that enables malicious actors to execute arbitrary web scripts within the context of a victim's browser session.
The technical exploitation mechanism leverages the improper sanitization of user-supplied input within CSS style definitions. When users submit content containing malicious CSS code with background:url properties embedded within glow or shadow tags, the forum software fails to adequately validate or escape these inputs before rendering them in the browser. This allows attackers to inject JavaScript code that executes in the victim's browser context, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The vulnerability specifically targets the CSS rendering engine's interpretation of style attributes, making it particularly insidious as it can bypass traditional input validation measures that focus on HTML tags rather than CSS properties.
From an operational impact perspective, this vulnerability poses significant risks to forum administrators and users alike. Attackers can exploit this weakness to steal session cookies, redirect users to phishing sites, deface forum content, or establish persistent malicious presence within the forum environment. The attack requires no special privileges beyond normal user access to the forum, making it particularly dangerous as it can be exploited by anyone with registration access. The vulnerability's impact extends beyond simple data theft to include potential compromise of the entire forum infrastructure, as successful exploitation can lead to further attacks against the underlying server or other connected systems.
Security professionals should consider this vulnerability in the context of CWE-79, which specifically addresses cross-site scripting flaws in software applications. The flaw aligns with ATT&CK technique T1566.001, which covers spearphishing attachments, and T1059.007, which involves command and scripting interpreter JavaScript. Organizations should implement immediate mitigations including input validation of all user-supplied content, particularly CSS style attributes, and consider implementing Content Security Policy headers to limit script execution. The vulnerability also highlights the importance of regular security updates and proper sanitization of all user-generated content, as it demonstrates how seemingly benign CSS properties can become attack vectors when not properly validated. Patch management becomes critical in addressing this issue, as the vulnerability affects specific versions of YaBB software that have known remediation paths through official updates and patches provided by the software vendor.