CVE-2025-11710 is a security vulnerability identified in Mozilla Firefox and Thunderbird that allows a compromised web process to exploit malicious inter-process communication (IPC) messages to cause the privileged browser process to leak blocks of its memory. The vulnerability arises because the IPC message handling mechanism does not adequately validate or sanitize messages from less privileged web processes, enabling them to access memory regions they should not. A successful attack requires the attacker to first compromise a web process, which can be achieved by delivering malicious web content or exploiting other browser-based attack vectors. Once compromised, the attacker can send crafted IPC messages to the privileged process, causing it to disclose memory contents that may include sensitive data such as authentication tokens, cookies, or other confidential information. This vulnerability affects Firefox versions earlier than 144, Firefox ESR versions earlier than 115.29 and 140.4, and Thunderbird versions earlier than 144 and 140.4. Although no known exploits are currently reported in the wild, the vulnerability poses a significant risk due to the potential for information leakage. Mozilla has published the vulnerability but has not yet assigned a CVSS score. The flaw is particularly concerning because it crosses process boundaries, violating the security model that isolates web content from privileged browser components. This can lead to confidentiality breaches and potentially facilitate further attacks if sensitive data is exposed. The vulnerability does not require user interaction beyond visiting a malicious website or loading malicious content, increasing its risk profile. The lack of patches or links to updates in the provided information suggests that affected organizations should prioritize upgrading to the fixed versions once available or apply interim mitigations. Monitoring IPC traffic and restricting browser extensions can reduce exposure. Given the widespread use of Firefox and Thunderbird in Europe, the vulnerability could impact a broad range of users and organizations, especially those in sectors with high data sensitivity.

The primary impact of CVE-2025-11710 is the unauthorized disclosure of sensitive information due to memory leakage from the privileged browser process to a compromised web process. For European organizations, this could lead to exposure of confidential data such as session tokens, personal information, or corporate secrets, undermining data confidentiality and potentially enabling further exploitation or lateral movement within networks. The vulnerability could affect organizations relying on Firefox and Thunderbird for daily operations, including government agencies, financial institutions, healthcare providers, and critical infrastructure operators. The ease of exploitation after compromising a web process increases the risk, especially in environments where users frequently access untrusted web content or where targeted phishing campaigns are common. Although availability and integrity impacts are limited, the breach of confidentiality alone can have severe regulatory and reputational consequences under GDPR and other European data protection laws. Additionally, the cross-process nature of the vulnerability challenges the browser’s security boundary, potentially facilitating more complex attacks if combined with other vulnerabilities. The lack of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits rapidly after public disclosure. Organizations with high Firefox and Thunderbird usage and those in sectors with stringent data protection requirements are particularly vulnerable.

To mitigate CVE-2025-11710, European organizations should take the following specific actions: 1) Immediately plan and execute upgrades to Mozilla Firefox version 144 or later, Firefox ESR versions 115.29 or later and 140.4 or later, and Thunderbird versions 144 or later and 140.4 or later as soon as patches are available. 2) Until patches are applied, restrict access to untrusted or potentially malicious web content by enforcing strict web filtering policies and using browser security configurations that limit exposure to risky sites. 3) Monitor inter-process communication within Firefox and Thunderbird for unusual or unexpected IPC messages that could indicate exploitation attempts. 4) Disable or tightly control browser extensions and plugins, as these can be vectors for compromising web processes. 5) Employ endpoint detection and response (EDR) tools to detect anomalous browser behavior indicative of process compromise. 6) Educate users about phishing and social engineering risks that could lead to web process compromise. 7) Implement network segmentation and least privilege principles to limit the impact of any potential compromise. 8) Regularly audit and update browser configurations and security settings to align with best practices. These measures, combined with timely patching, will reduce the risk of exploitation and limit potential damage.