CVE-2025-28880 is a reflected Cross-site Scripting (XSS) vulnerability in jotis Blue Captcha, a web security tool designed to prevent automated bot interactions. The vulnerability stems from improper neutralization of user-supplied input during web page generation, which allows attackers to inject malicious JavaScript code that is reflected back to users. This flaw affects all versions of Blue Captcha up to and including 1.7.4. When exploited, an attacker can craft a specially crafted URL or input that, when visited by a victim, executes arbitrary scripts in the victim's browser context. This can lead to theft of session cookies, redirection to malicious sites, or execution of unauthorized actions on behalf of the user. The vulnerability does not require authentication, making it easier for remote attackers to exploit. Although no public exploits have been reported yet, the nature of reflected XSS means that exploitation is straightforward once the vulnerability is known. The lack of a CVSS score indicates that the vulnerability is newly disclosed and awaiting further assessment. The vulnerability affects the integrity and confidentiality of user sessions and data, and can also impact availability if used to perform malicious actions that disrupt service. Blue Captcha is used as a security measure on websites, so its compromise can undermine overall site security.

The primary impact of CVE-2025-28880 is the compromise of user confidentiality and integrity through the execution of malicious scripts in users' browsers. Attackers can steal session cookies, enabling account takeover, or perform actions on behalf of users without their consent. This can lead to unauthorized access, data leakage, and potential further exploitation within the affected web application. The vulnerability can also damage the reputation of organizations by exposing users to phishing or malware distribution. Since Blue Captcha is a security control, its compromise may reduce the effectiveness of bot mitigation, increasing exposure to automated attacks. The ease of exploitation without authentication broadens the attack surface, potentially affecting a wide range of users. While availability impact is less direct, persistent exploitation could lead to denial of service or degraded user experience. Organizations relying on Blue Captcha for security should consider this vulnerability a significant risk to their web applications and user trust.

To mitigate CVE-2025-28880, organizations should first monitor for and apply any official patches or updates released by jotis for Blue Captcha beyond version 1.7.4. In the absence of an immediate patch, implement strict input validation and output encoding on all user-supplied data that is reflected in web pages to prevent script injection. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. Review and harden web application firewall (WAF) rules to detect and block reflected XSS attack patterns targeting Blue Captcha endpoints. Conduct thorough security testing, including automated and manual XSS testing, on web pages integrating Blue Captcha. Educate developers and administrators about secure coding practices related to input handling. Consider temporarily disabling or replacing Blue Captcha with alternative CAPTCHA solutions if patching is delayed and risk is high. Finally, monitor logs and user reports for signs of exploitation attempts or suspicious activity related to this vulnerability.