CVE-2025-46445 is a Stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79, affecting the pReya External Markdown component. This vulnerability arises due to improper neutralization of input during web page generation, allowing malicious actors to inject and persist executable scripts within the application’s content. Specifically, the External Markdown module fails to adequately sanitize or encode user-supplied input before rendering it in web pages, enabling attackers to embed malicious JavaScript code. When other users or administrators access the affected pages, the injected scripts execute in their browsers under the context of the vulnerable application, potentially leading to session hijacking, credential theft, unauthorized actions, or distribution of malware. The vulnerability affects External Markdown versions up to 0.0.1, with no patch currently available. No known exploits have been reported in the wild as of the publication date (April 24, 2025). The vulnerability was identified and assigned by Patchstack and is recognized by CISA enrichment, indicating its relevance in cybersecurity monitoring. Stored XSS is particularly dangerous because the malicious payload is permanently stored on the server and served to multiple users, increasing the attack surface and impact. The lack of a CVSS score necessitates an independent severity assessment based on the vulnerability’s characteristics.

For European organizations using pReya External Markdown, this vulnerability poses a significant risk to confidentiality, integrity, and availability of web applications. Attackers exploiting this flaw can execute arbitrary scripts in users’ browsers, potentially leading to theft of sensitive information such as authentication tokens, personal data, or corporate credentials. This can facilitate further attacks like privilege escalation or lateral movement within networks. The integrity of displayed content can be compromised, misleading users or damaging organizational reputation. Additionally, attackers might leverage the vulnerability to distribute malware or conduct phishing campaigns, impacting availability by disrupting normal operations or causing service outages. Given the stored nature of the XSS, the risk extends to all users accessing the compromised content, including administrators, increasing the potential damage. European organizations in sectors with high web presence—such as finance, healthcare, government, and critical infrastructure—are particularly vulnerable due to the sensitivity of their data and regulatory requirements like GDPR. The absence of known exploits provides a window for proactive mitigation, but the medium severity rating suggests that exploitation is feasible and impactful if left unaddressed.

1. Immediate implementation of input validation and output encoding: Organizations should enforce strict sanitization of all user inputs processed by the External Markdown component, employing context-aware encoding (e.g., HTML entity encoding) before rendering content. 2. Employ Content Security Policy (CSP): Deploy a robust CSP to restrict the execution of unauthorized scripts and reduce the impact of potential XSS payloads. 3. Monitor and audit content: Regularly scan stored content for suspicious scripts or anomalies that may indicate exploitation attempts. 4. Isolate vulnerable components: If feasible, restrict access to the External Markdown module or disable it temporarily until a patch is available. 5. User privilege management: Limit the ability to submit or edit markdown content to trusted users only, reducing the attack surface. 6. Keep abreast of vendor updates: Engage with pReya for timely patches or workarounds and apply them promptly once released. 7. Educate users and administrators: Train personnel to recognize phishing or suspicious behaviors that may result from XSS exploitation. 8. Implement web application firewalls (WAFs): Configure WAF rules to detect and block common XSS attack patterns targeting the External Markdown interface.