CVE-2021-25262 is a vulnerability identified in Yandex Browser for Android versions prior to 21.3.0. It is classified under CWE-116, which pertains to improper encoding or escaping of output. Specifically, this vulnerability allows remote attackers to conduct an IDN (Internationalized Domain Name) homograph attack. In such attacks, visually similar characters from different scripts are used to create deceptive domain names that appear identical or very similar to legitimate ones. Due to improper encoding or escaping in the browser's handling of domain names, users can be tricked into visiting malicious websites that impersonate trusted domains. This can lead to phishing, credential theft, or malware delivery. The CVSS 4.0 base score is 6.9 (medium severity), with an attack vector of network (no physical access needed), low attack complexity, no privileges or user interaction required, but user interaction is marked as required (UI:A), and a high impact on confidentiality. No known exploits are reported in the wild as of the published date. The vulnerability affects the Android version of Yandex Browser, a product primarily used in Russia and some neighboring countries but also by users in Europe. The issue was reserved in January 2021 and published in May 2025, indicating a delayed disclosure or update. The lack of patch links suggests users should upgrade to version 21.3.0 or later where the issue is fixed. Overall, this vulnerability exploits the browser's failure to properly encode or escape domain names, enabling attackers to deceive users with spoofed URLs, potentially leading to sensitive data compromise.

For European organizations, this vulnerability poses a significant risk primarily in the context of phishing and social engineering attacks. Attackers can craft URLs that appear to be from trusted entities, such as banks, government portals, or corporate services, to deceive employees or customers into divulging credentials or installing malware. Given the medium severity and the requirement for user interaction, the threat is more pronounced in environments where Yandex Browser is used on Android devices, including by employees or partners. The confidentiality of sensitive information is at risk, which can lead to data breaches, financial fraud, or unauthorized access to corporate resources. The integrity and availability impacts are limited but could occur if attackers leverage the vulnerability as part of a broader attack chain. Since no exploits are known in the wild, the immediate risk is moderate; however, the potential for targeted attacks against European entities that use Yandex Browser or have users with it installed remains. This is especially relevant for sectors with high-value targets such as finance, government, and critical infrastructure, where phishing attacks are common and can have severe consequences.

European organizations should implement the following specific mitigations: 1) Enforce policies to restrict or monitor the use of Yandex Browser on corporate Android devices, ensuring that only updated versions (21.3.0 or later) are installed. 2) Deploy URL filtering and anti-phishing solutions that can detect and block homograph attacks, including those exploiting IDN spoofing. 3) Educate users about the risks of clicking on suspicious links, emphasizing the possibility of visually deceptive URLs, especially in emails or messaging apps. 4) Implement multi-factor authentication (MFA) across critical services to reduce the impact of credential theft resulting from phishing. 5) Monitor network traffic for unusual DNS queries or connections to suspicious domains that may indicate exploitation attempts. 6) Collaborate with mobile device management (MDM) solutions to enforce browser updates and restrict installation of unapproved browsers. 7) Encourage users to verify URLs carefully and use bookmarks or direct navigation for sensitive sites. These measures go beyond generic advice by focusing on controlling browser versions, enhancing detection of homograph attacks, and user awareness specific to this vulnerability.