CVE-2025-31029 identifies a stored Cross-site Scripting (XSS) vulnerability in the bingu replyMail product, specifically in versions up to and including 1.2.0. This vulnerability results from improper neutralization of user-supplied input during the generation of web pages, allowing malicious scripts to be stored and later executed in the context of other users’ browsers. The vulnerability is classified as a stored XSS, meaning the malicious payload is saved on the server and delivered to users when they access affected pages, increasing the potential impact compared to reflected XSS. The CVSS v3.1 score is 5.4 (medium severity), with an attack vector of network (AV:N), low attack complexity (AC:L), requiring privileges (PR:L), and user interaction (UI:R). The scope is changed (S:C), indicating that exploitation affects resources beyond the vulnerable component. The impact affects confidentiality and integrity partially (C:L/I:L) but does not affect availability (A:N). Exploitation requires an attacker to have some level of privileges on the system and to trick a user into interacting with the malicious content, such as clicking a link or viewing a crafted email. The vulnerability could allow attackers to steal session tokens, perform actions on behalf of users, or manipulate displayed content, potentially leading to further compromise or data leakage. No known exploits are currently reported in the wild, but the vulnerability’s presence in a mail-related product increases the risk of targeted phishing or social engineering campaigns. The lack of available patches at the time of publication means organizations must rely on interim mitigations until official fixes are released.

For European organizations, the impact of CVE-2025-31029 can be significant, especially for those relying on bingu replyMail for email processing or customer communications. Stored XSS can lead to unauthorized disclosure of sensitive information, session hijacking, and manipulation of user interactions, undermining trust and potentially violating data protection regulations such as GDPR. The partial compromise of confidentiality and integrity could expose personal data or internal communications. Since the vulnerability requires some privileges and user interaction, insider threats or targeted phishing attacks could exploit this vector. The disruption to email workflows or reputational damage from successful attacks could have operational and financial consequences. Organizations in sectors like finance, healthcare, and government, where email is critical and data sensitivity is high, face elevated risks. Additionally, the cross-site scripting vulnerability could be leveraged as a foothold for further attacks within corporate networks, increasing the overall threat landscape.

To mitigate CVE-2025-31029, organizations should implement multiple layers of defense. First, apply strict input validation and sanitization on all user-supplied data before it is stored or rendered, ensuring that scripts or HTML tags are neutralized. Employ context-aware output encoding to prevent script execution in browsers. Restrict user privileges to the minimum necessary, limiting the ability of attackers to inject malicious content. Deploy Content Security Policy (CSP) headers to reduce the impact of any injected scripts by restricting sources of executable code. Monitor logs for unusual input patterns or repeated failed attempts to inject scripts. Educate users about the risks of interacting with suspicious emails or links, as user interaction is required for exploitation. Until official patches are available, consider isolating or restricting access to the replyMail system, especially from untrusted networks. Regularly update and audit the software environment to detect and remediate vulnerabilities promptly. Engage with the vendor for timely patch releases and verify the integrity of updates before deployment.