CVE-2025-10890 is a side-channel information leakage vulnerability found in the V8 JavaScript engine used by Google Chrome versions prior to 140.0.7339.207. This vulnerability allows a remote attacker to leak cross-origin data by crafting a malicious HTML page that exploits the side-channel behavior of V8. Side-channel attacks typically exploit indirect information such as timing, cache behavior, or memory access patterns to infer sensitive data that should be inaccessible due to same-origin policy restrictions. In this case, the attacker can bypass Chrome's cross-origin protections and extract data from other origins loaded in the browser, potentially exposing sensitive user information such as authentication tokens, personal data, or session details. The vulnerability does not require the attacker to have direct access to the victim's system but relies on the victim visiting a malicious webpage. Although no known exploits are currently reported in the wild, the severity is classified as high by Chromium security due to the potential for significant privacy breaches and data leakage. The vulnerability was publicly disclosed on September 24, 2025, and affects all Chrome versions before 140.0.7339.207. No CVSS score has been assigned yet, and no official patch links are provided in the data, but updating to version 140.0.7339.207 or later is implied as the remediation step.

For European organizations, this vulnerability poses a substantial risk to confidentiality and user privacy. Organizations relying heavily on Chrome for web-based applications, especially those handling sensitive or regulated data (e.g., financial institutions, healthcare providers, government agencies), could face data leakage risks if employees or users visit malicious websites. The cross-origin data leakage could lead to unauthorized disclosure of internal session tokens, personal identifiable information (PII), or proprietary data accessible via web applications. This could result in compliance violations under GDPR and other data protection regulations, reputational damage, and potential financial losses. Additionally, attackers could leverage this vulnerability to conduct targeted espionage or reconnaissance against European entities by crafting web content that extracts sensitive information from users’ browsers. The lack of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits rapidly after public disclosure.

European organizations should prioritize updating Google Chrome to version 140.0.7339.207 or later as soon as possible to remediate this vulnerability. Beyond patching, organizations should implement strict web browsing policies, including restricting access to untrusted or unknown websites through network-level controls or browser security configurations. Deploying browser isolation or sandboxing technologies can limit the impact of malicious web content. Security awareness training should emphasize the risks of visiting suspicious websites and encourage cautious browsing behavior. For high-risk environments, consider using browser extensions or enterprise policies that disable JavaScript execution on untrusted sites or implement Content Security Policy (CSP) headers to reduce exposure to malicious scripts. Monitoring network traffic for unusual outbound data flows may help detect exploitation attempts. Finally, organizations should stay informed about updates from Google and apply security patches promptly.