CVE-2026-103664 in MISP
Summary
by MITRE • 10/01/2026
MISP contains a reflected cross-site scripting (XSS) vulnerability in the analyst data notes panel. The seed path parameter, supplied by the user via the URL, was passed directly into inline JavaScript within the rendered HTML response without any sanitization or type enforcement.
An attacker who can convince an authenticated MISP user to navigate to a crafted URL (for example, via a phishing link) can inject arbitrary JavaScript that executes in the victim's browser context. This may allow the attacker to read session tokens, manipulate the page, or perform actions on behalf of the victim.
Preconditions:
- The victim must be authenticated to MISP and access the analyst data view for an attribute or object.
- The attacker must supply a malicious seed value in the URL path.
Impact:
- Execution of arbitrary JavaScript in the victim's browser session.
- Potential theft of session credentials or sensitive data visible in the page.
- Manipulation of the analyst data interface.
Affected: MISP versions prior to the fix (commit 58925dbf0, post v2.5.48).
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Analysis
by VulDB Data Team • 10/01/2026
The vulnerability identified within the Malware Information Sharing Platform involves a reflected cross-site scripting flaw located in the analyst data notes panel. This security defect stems from improper input validation and output encoding practices during the rendering of web pages. Specifically, the seed path parameter is accepted directly from user-supplied URL inputs without undergoing any form of sanitization or type enforcement before being embedded into inline JavaScript code within the HTML response. Because the application fails to escape special characters that have meaning in a script context, such as quotes and semicolons, an attacker can inject malicious scripts that are interpreted by the victim's web browser as legitimate commands belonging to the MISP application itself. This represents a classic instance of input validation failure where trusted execution contexts are compromised through untrusted data sources.
From a technical perspective, this flaw aligns with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. The vulnerability is classified under the ATT&CK technique T1059, specifically Command and Scripting Interpretation via JavaScript, as it allows for the execution of arbitrary code within the browser environment. The root cause lies in the server-side logic that constructs the HTML response by concatenating user input directly into script blocks without applying context-aware encoding. This lack of defense-in-depth means that even if other security controls are present, this specific vector remains open to exploitation because the application treats unvalidated URL parameters as safe for direct inclusion in executable code segments.
The operational impact of this vulnerability is significant due to its potential for session hijacking and data exfiltration. An attacker who can persuade an authenticated MISP user to visit a crafted URL, typically through social engineering or phishing campaigns, gains the ability to execute arbitrary JavaScript within the victim's browser context. This capability allows the malicious script to access sensitive information stored in local storage or cookies, including session tokens that authenticate the user to the platform. By stealing these credentials, an attacker can impersonate the legitimate user, gaining unauthorized access to shared intelligence data and potentially modifying threat indicators without detection. Furthermore, the ability to manipulate the page content enables phishing attacks against other users within the same organization by altering interface elements or displaying fake login prompts that mimic the authentic MISP application.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The primary fix involves updating the MISP installation to a version post v2.5.48, specifically incorporating commit 58925dbf0 which addresses this input validation gap. For environments where patching is not immediately feasible, network-level controls such as Web Application Firewalls can be configured to detect and block requests containing suspicious script patterns in URL parameters. Additionally, developers should implement strict output encoding practices that convert special characters into their HTML entity equivalents before rendering them in any context, particularly within JavaScript blocks. Implementing Content Security Policy headers further restricts the execution of inline scripts, providing an additional layer of defense against cross-site scripting attacks even if input validation fails. Regular security audits and code reviews focusing on data flow from user inputs to output contexts are essential for preventing similar vulnerabilities in future development cycles.