CVE-2025-53600 is a high-severity security vulnerability identified in the NAVER Whale browser, specifically versions prior to 4.32.315.22. The vulnerability is categorized under CWE-346, which relates to Origin Validation Errors. This flaw allows an attacker to bypass the Same-Origin Policy (SOP) when the browser is operating in a dual-tab environment. The Same-Origin Policy is a critical security mechanism implemented in web browsers to restrict how documents or scripts loaded from one origin can interact with resources from another origin. Bypassing this policy can enable malicious websites or scripts to access or manipulate data from other sites without proper authorization. The vulnerability does not require any user interaction or privileges (AV:N/AC:L/PR:N/UI:N), making it remotely exploitable over the network with low attack complexity. The CVSS v3.1 base score of 7.5 reflects the high impact on integrity (I:H) with no impact on confidentiality or availability. The flaw could allow attackers to inject or modify content in another tab's context, potentially leading to session hijacking, unauthorized transactions, or manipulation of sensitive data displayed in the browser. Although no known exploits are currently reported in the wild, the vulnerability's nature and ease of exploitation make it a significant risk. NAVER Whale browser is a Chromium-based browser popular primarily in South Korea but also used in some European markets, especially among Korean expatriates and businesses with ties to Korea. The lack of a patch link indicates that a fix may still be pending or not yet publicly released, increasing the urgency for mitigation.

For European organizations, this vulnerability poses a substantial risk, particularly for those using NAVER Whale browser in environments where sensitive web applications are accessed. The ability to bypass the Same-Origin Policy can lead to unauthorized manipulation of web sessions, data theft, or injection of malicious scripts, compromising the integrity of web-based workflows. Organizations in sectors such as finance, healthcare, and government, where data integrity is paramount, could face targeted attacks exploiting this flaw. Additionally, multinational companies with Korean business relations or employees using Whale browser may inadvertently expose their internal systems to cross-origin attacks. The vulnerability could also facilitate advanced phishing or social engineering attacks by allowing attackers to present manipulated content from trusted origins. Given the browser’s niche but growing user base, the impact is moderate but focused, with potential for escalation if combined with other vulnerabilities or social engineering tactics.

1. Immediate mitigation involves advising users and organizations to upgrade NAVER Whale browser to version 4.32.315.22 or later once the patch is released. Until then, users should consider switching to alternative browsers with robust SOP enforcement. 2. Implement network-level controls such as web filtering to restrict access to untrusted or suspicious websites that could exploit this vulnerability. 3. Employ Content Security Policy (CSP) headers on web applications to limit the execution of unauthorized scripts and reduce the risk of cross-origin attacks. 4. Educate users about the risks of using niche browsers for sensitive activities and encourage adherence to corporate browser policies. 5. Monitor network traffic and browser behavior for anomalies indicative of cross-origin attacks or session manipulation. 6. For organizations developing web applications, conduct thorough testing against SOP bypass scenarios and reinforce origin validation logic on the server side to prevent unauthorized requests.