CVE-2026-42779 Apache MINA vulnerable to Deserialization of Untrusted Data (CVE-2026-41635 Incomplete Fix)

What is CVE-2026-42779?

CVE-2026-42779 is a critical unsafe deserialization vulnerability in Apache MINA, published on 1 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

The fix for CVE-2026-41635 was not applied to the 2.1.X and 2.2.X branches. Here was the original issue description:

Apache MINA's AbstractIoBuffer.resolveClass() contains two branches, one of them (for static classes or primitive types) does not check the class at all, bypassing the classname allowlist and allowing arbitrary code to be executed.

The fix checks if the class is present in the accepted class filter before calling Class.forName().

Affected versions are Apache MINA 2.1.0 <= 2.1.11, and 2.2.0 <= 2.2.6.

The problem is resolved in Apache MINA 2.1.12, and 2.2.7 by applying the classname allowlist earlier.

Affected are applications using Apache MINA that call IoBuffer.getObject().

Applications using Apache MINA are advised to upgrade.

Weakness: CWE-502

Which versions are affected by CVE-2026-42779?

4 open source packages ship an affected version, including org.apache.mina:mina-core. It affects 1 product.

Products include Apache Mina.

How do I fix CVE-2026-42779?

Upgrade org.apache.mina:mina-core to a fixed version for your release line: 2.1.12 or 2.2.7.

Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.

Is CVE-2026-42779 being exploited?

There is no known exploitation of CVE-2026-42779 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

Other vulnerabilities in Apache MINA

• CVE-2024-52046 Apache MINA: MINA applications using unbounded deserialization may allow RCE Critical 10.0
• CVE-2026-47065 Apache MINA: Critical Deserialization Allow-list Bypass via resolveProxyClass - ZDRES-232 Critical 9.8
• CVE-2026-42778 Apache MINA: CWE-502 Deserialization of Untrusted Data (take 2) Critical 9.8
• CVE-2026-41409 Apache MINA: CWE-502 Deserialization of Untrusted Data Critical 9.8
• CVE-2026-41635 Apache MINA vulnerable to Deserialization of Untrusted Data Critical 9.8

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as CLEANSTART-2026-BL56844, CLEANSTART-2026-BZ36628, CLEANSTART-2026-GX72554, CLEANSTART-2026-OA86138, CLEANSTART-2026-YJ76676, ECHO-5cd5-f8bb-3443 and 9 more.