CVE-2025-10536 is an information disclosure vulnerability identified in the Networking Cache component of Mozilla Firefox, affecting versions prior to Firefox 143 and Firefox ESR versions prior to 140.3. The vulnerability pertains to the way Firefox handles cached network data, potentially allowing unauthorized access to sensitive information stored in the cache. Although specific technical details such as the exact nature of the flaw or the attack vector are not provided, information disclosure vulnerabilities in browser cache components typically arise from improper access controls or flaws in cache isolation mechanisms. This can lead to leakage of sensitive data such as browsing history, session tokens, or other cached content that should remain confidential. The vulnerability has been officially published but lacks a CVSS score and no known exploits are currently reported in the wild. Given that Firefox is a widely used web browser, this vulnerability could be leveraged by attackers to extract sensitive user data if exploited, especially in scenarios where malicious websites or scripts can trigger cache reads beyond their privilege scope. The absence of a patch link suggests that remediation may be pending or that users should upgrade to the fixed versions (Firefox 143 or ESR 140.3) once available.

For European organizations, the impact of this vulnerability could be significant depending on the sensitivity of the data accessed through the cache and the deployment scale of Firefox within the organization. Information disclosure can compromise confidentiality, potentially exposing internal browsing activity, authentication tokens, or other sensitive cached data to attackers. This could facilitate further attacks such as session hijacking, targeted phishing, or espionage. Organizations in sectors with stringent data protection requirements, such as finance, healthcare, and government, may face regulatory and reputational risks if sensitive data is leaked. Additionally, since Firefox is popular among both private users and enterprises in Europe, a successful exploitation could affect a broad user base. However, the lack of known exploits and the requirement to target cached data limits the immediate risk. Still, the vulnerability underscores the need for timely patching to prevent potential exploitation, especially in environments where users access sensitive web applications via Firefox.

European organizations should prioritize upgrading all Firefox installations to version 143 or later, or Firefox ESR 140.3 or later, as soon as these versions are available to ensure the vulnerability is patched. Until upgrades are possible, organizations should consider implementing network-level controls to restrict access to untrusted or malicious websites that could attempt to exploit this vulnerability. Employing browser security policies that limit cache usage or isolate browsing sessions (e.g., using container tabs or profile separation) can reduce the risk of cross-site cache data leakage. Additionally, organizations should educate users about the risks of visiting untrusted sites and encourage the use of security extensions that enhance privacy and cache control. Monitoring network traffic for unusual data exfiltration patterns and maintaining up-to-date endpoint protection can help detect and prevent exploitation attempts. Finally, organizations should stay informed through Mozilla security advisories for any patches or additional mitigation guidance.