CVE-2026-76203 in Pentestify
Summary
by MITRE • 08/19/2026
Incorrect Behavior Order: Validate Before Canonicalize in the report theme CSS sanitizer in maalfer Pentestify 1.2.0 through 2.3.2 allows an authenticated user to force outbound HTTP requests from other users' browsers, disclosing their IP address and User-Agent, via CSS hex escapes that reconstruct the url() function and evade the sanitizer blocklist
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Analysis
by VulDB Data Team • 08/19/2026
The vulnerability identified in maalfer Pentestify versions 1.2.0 through 2.3.2 represents a critical flaw within its report theme Cascading Style Sheets (CSS) sanitization logic, specifically categorized under CWE-840: Incorrect Behavior Order: Validate Before Canonicalize. This architectural defect allows an authenticated attacker to bypass security controls designed to prevent Cross-Site Scripting and data exfiltration via CSS injection. The core issue lies in the sequence of operations performed by the sanitizer engine when processing user-supplied input for report themes. Instead of first normalizing or canonicalizing the input string to resolve all potential encoding variations, the system performs validation checks against a blocklist of malicious patterns before this normalization step occurs. This ordering error creates a window where obfuscated payloads can slip through initial security filters because they do not yet match the literal strings defined in the blocklist.
The technical mechanism exploited by this vulnerability involves the use of CSS hex escapes to reconstruct the url() function, which is commonly used for loading external resources such as images or stylesheets. By encoding specific characters within a URL using hexadecimal notation, an attacker can craft a malicious style rule that appears benign during the initial validation phase. For instance, instead of writing a direct http:// request in plain text, the attacker utilizes CSS escape sequences to represent parts of the domain name and protocol scheme. When the browser parses this malformed but syntactically valid CSS, it automatically decodes these hex escapes before rendering the page. This decoding process effectively reconstructs the url() directive with an external malicious endpoint that was not present in the original input string submitted by the attacker.
The operational impact of this vulnerability is significant for organizations relying on Pentestify for managing security assessments and reporting. Since the flaw permits forced outbound HTTP requests from the context of other users' browsers, it facilitates a form of Cross-Site Request Forgery (CSRF) combined with data exfiltration. An authenticated attacker can craft a malicious report theme that, when viewed by another user such as an administrator or fellow pentester, triggers a network request to a server controlled by the attacker. This action discloses sensitive client-side information including the victim's IP address and User-Agent string. In more complex attack scenarios involving cookies or session tokens stored in CSS variables or accessed via subsequent JavaScript execution triggered by the style change, this could lead to full account takeover or deeper internal network reconnaissance.
This behavior aligns with ATT&CK technique T1059.007: Command and Scripting Interpreter: JavaScript, specifically when used for data exfiltration through browser-based mechanisms, although it primarily manifests as a CSS injection leading to outbound requests (T1048: Exfiltration Over Alternative Protocol). The vulnerability underscores the importance of robust input handling in web application frameworks. To mitigate this risk, developers must ensure that all user-supplied content undergoes canonicalization before any security validation or filtering is applied. This involves decoding all encoding schemes such as hex escapes, Unicode escapes, and HTML entities to their raw character equivalents prior to checking against blocklists. Additionally implementing a Content Security Policy (CSP) with strict directives regarding connect-src can restrict the domains from which resources are loaded, thereby neutralizing the impact of any successful CSS injection even if validation bypasses occur. Regular security audits focusing on input/output encoding practices and adopting defense-in-depth strategies that include both server-side sanitization and client-side policy enforcement are essential to preventing such exploitation vectors in future versions of the software.