CVE-2025-52571 is a critical improper authentication vulnerability (CWE-287) affecting the Hikka Telegram userbot, specifically all versions prior to 1.6.2, including most forks derived from these versions. Hikka is a userbot framework that automates Telegram accounts, often used for managing chats, automating tasks, or integrating Telegram with other services. The vulnerability allows an unauthenticated attacker to bypass authentication mechanisms, thereby gaining unauthorized access to the victim's Telegram account as well as full control over the server hosting the userbot. This implies that an attacker can impersonate the legitimate user on Telegram, potentially accessing private messages, contacts, and other sensitive information. Additionally, server-level access enables the attacker to execute arbitrary commands, deploy malware, or pivot to other network resources. The vulnerability is remotely exploitable over the network without any privileges or prior authentication, but requires user interaction (likely triggering the bot or sending crafted messages). The CVSS v3.1 score of 9.7 (critical) reflects the high impact on confidentiality, integrity, and availability, combined with low attack complexity and no required privileges. No known workarounds exist, and the issue is fixed only in version 1.6.2 and later. Given the widespread use of Telegram and the popularity of userbots like Hikka in automation and integration scenarios, this vulnerability poses a significant risk to users and organizations relying on these tools.

For European organizations, the impact of this vulnerability is substantial. Telegram is widely used across Europe for both personal and professional communication, including by journalists, activists, and businesses. Organizations using Hikka userbots for automating Telegram workflows risk unauthorized disclosure of sensitive communications and credentials. The attacker’s ability to fully control the server hosting the bot can lead to lateral movement within corporate networks, data exfiltration, and deployment of ransomware or other malware. This is especially critical for sectors with high confidentiality requirements such as finance, healthcare, and government agencies. Furthermore, compromised Telegram accounts can be used for social engineering attacks, spreading misinformation, or conducting fraudulent activities. The lack of workarounds means that until systems are updated, the risk remains high. The vulnerability also undermines trust in automation tools and could disrupt business operations relying on Telegram integrations.

1. Immediate upgrade to Hikka version 1.6.2 or later is mandatory to patch the vulnerability. 2. Conduct an audit of all Telegram userbots deployed within the organization to identify any running vulnerable versions or forks. 3. Restrict server access and isolate servers running userbots from critical internal networks to limit potential lateral movement in case of compromise. 4. Implement multi-factor authentication (MFA) on Telegram accounts where possible to add an additional layer of protection, although this may not fully mitigate the vulnerability. 5. Monitor Telegram account activity for unusual behavior such as unexpected messages or login notifications. 6. Employ network-level monitoring and intrusion detection systems to detect anomalous traffic or command execution on servers hosting userbots. 7. Educate users and administrators about the risks of running outdated userbot software and the importance of timely updates. 8. Consider temporarily disabling userbots if immediate patching is not feasible, especially in high-risk environments. 9. Review and harden server configurations, including limiting permissions and applying the principle of least privilege to the userbot service accounts.