Multiple nginx Vulnerabilities Discovered in Ubuntu Security Advisory

On June 3, 2026, Ubuntu published a security advisory detailing multiple vulnerabilities in nginx affecting various Ubuntu LTS versions. Key issues include improper handling of memory operations in the ngx_mail_smtp_module (CVE-2025-53859), which could leak sensitive information, and flaws in the ngx_http_dav_module that could lead to denial of service (CVE-2026-27654). Other vulnerabilities could allow attackers to insert plaintext data into responses (CVE-2026-1642) and cause crashes (CVE-2026-27651). These vulnerabilities impact Ubuntu 20.04, 18.04, 16.04, and 14.04 LTS. Administrators are urged to update their systems to mitigate these risks. The advisory emphasizes the critical nature of these vulnerabilities, particularly for systems exposed to untrusted networks.

Key Points: • Multiple critical vulnerabilities in nginx affect several Ubuntu LTS versions. • CVE-2025-53859 could leak sensitive information during SMTP authentication. • Immediate updates are recommended to mitigate risks associated with these vulnerabilities.