Apache MINA Deserialization Vulnerability (CVE-2026-42778) Hits Critical

The National Vulnerability Database has issued a critical advisory for CVE-2026-42778, a deserialization vulnerability in Apache MINA. This flaw, rated 9.8 CVSS, stems from an incomplete fix for a prior issue (CVE-2024-52046). The core problem, according to the National Vulnerability Database, is that the classname allowlist — intended to restrict deserialization to safe classes — was applied too late. This delay allows static initializers in malicious classes to execute before the allowlist takes effect, bypassing security controls.

Specifically, Apache MINA versions 2.1.0 through 2.1.11, and 2.2.0 through 2.2.6 are affected. The National Vulnerability Database states that applications utilizing Apache MINA and making calls to IoBuffer.getObject() are vulnerable. The fix, which applies the classname allowlist earlier in the process, is available in Apache MINA 2.1.12 and 2.2.7. This is a classic deserialization attack vector, exploitable without authentication, enabling remote code execution.

Attackers will target this because it’s a high-impact vulnerability in a widely used library. The ability to execute arbitrary code remotely with no prior authentication is the holy grail for initial access. Defenders need to understand that this isn’t just about the MINA library itself; it’s about every application that embeds MINA and exposes this deserialization vector. The attacker’s calculus is simple: find a public-facing application using vulnerable MINA, send a crafted payload, and own the box.