Source: security@huntr.dev
Cross-site Scripting (XSS) - Stored in GitHub repository usememos/memos prior to 0.9.1.
Stored Cross-Site Scripting (XSS) vulnerabilities in the usememos/memos application allow attackers to inject malicious JavaScript code into the application, potentially leading to account compromise, data theft, and session hijacking. This vulnerability affects versions prior to 0.9.1, enabling attackers to persistently compromise users through crafted content within the application.
Step 1: Payload Delivery: An attacker crafts a malicious payload containing JavaScript code (e.g., <script>alert('XSS')</script>).
Step 2: Payload Injection: The attacker submits the crafted payload as input into a vulnerable field within the usememos/memos application (e.g., creating a new memo or adding a comment).
Step 3: Payload Storage: The application stores the malicious payload in its database without proper sanitization or encoding.
Step 4: Payload Rendering: When a legitimate user views the memo or comment containing the payload, the application retrieves the stored data from the database.
Step 5: Script Execution: The user's browser renders the retrieved data, including the malicious JavaScript code, which is then executed within the user's browser context.
The vulnerability stems from insufficient input sanitization and output encoding within the usememos/memos application. Specifically, user-supplied input, such as memos or comments, is not properly validated or escaped before being stored in the database and subsequently rendered in the user's browser. This allows attackers to inject arbitrary HTML and JavaScript code. The root cause is a failure to implement proper input validation and output encoding (e.g., HTML entity encoding) when displaying user-generated content. The application trusts user input, leading to the execution of malicious scripts within the context of other users' sessions. This is a classic example of a stored XSS vulnerability.
While no specific APT groups are directly linked to this CVE, XSS vulnerabilities are commonly exploited by various threat actors, including those involved in credential harvesting, phishing, and malware distribution. This type of vulnerability is often used as an initial access vector. Not listed on CISA KEV.
Network traffic analysis: Look for unusual HTTP requests containing JavaScript code within memo or comment content.
Web application firewall (WAF) logs: Examine WAF logs for blocked requests containing XSS payloads.
Content Security Policy (CSP) violations: Monitor for CSP violations, which can indicate attempted XSS attacks.
Database query analysis: Review database queries for suspicious input patterns or unexpected HTML tags within user-generated content.
Forensic analysis: Examine application logs for evidence of malicious script injection attempts.
Upgrade to usememos/memos version 0.9.1 or later.
Implement input validation to sanitize user-supplied data, ensuring that only expected characters and formats are accepted.
Implement output encoding (e.g., HTML entity encoding) to escape special characters (e.g., <, >, &, ', ") before displaying user-generated content in HTML.
Implement a Content Security Policy (CSP) to restrict the sources from which the browser can load resources, mitigating the impact of successful XSS attacks.
Regularly scan the application for vulnerabilities using static and dynamic analysis tools.
Educate developers on secure coding practices to prevent future XSS vulnerabilities.