Vulnerability · Published May 1, 2026 · Assigned by apache

CVE-2026-42779Apache MINA: AbstractIoBuffer.resolveClass() null-clazz Branch Skips acceptMatchers Filter — Full Object Deserialization RCE (take 2)

Critical 9.8

In plain English

A critical-severity unsafe deserialization in Apache MINA from Apache Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.2% (higher than 69% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.8Critical

Exploit odds (30 days)1.2%top 31.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack tooling1Public PoC

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Maven	org.apache.mina:mina-core	2.1.12	GHSA-vf5j-865m-mq7c
Maven	org.apache.mina:mina-core	2.2.7	GHSA-vf5j-865m-mq7c
Ubuntu:25.10	mina2	no fix listed	UBUNTU-CVE-2026-42779
Ubuntu:26.10	mina2	no fix listed	UBUNTU-CVE-2026-42779

Affected products (as reported)

Vendor	Product	Versions
Apache Software Foundation	Apache MINA	2.2.X – through 2.2.62.1.X – through 2.1.11

Weakness: CWE-502 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

https://lists.apache.org/thread/fhlx5k91hrkgyzh7yk1nghrn3k27gxy0 vendor-advisory