Critical Arbitrary Code Execution Vulnerability CVE-2026-41635 in Apache MINA
Summary
The Centre for Cybersecurity Belgium issued a critical advisory warning of CVE-2026-41635, a CVSS 9.8 arbitrary code execution vulnerability in Apache MINA versions 2.0.0 through 2.0.27, 2.1.0 through 2.1.10, and 2.2.0 through 2.2.5. The vulnerability exists in the AbstractIoBuffer.resolveClass() method where one code path bypasses classname allowlist validation, enabling attackers to achieve arbitrary code execution through the IoBuffer.getObject() function. Organizations using affected Apache MINA instances are urged to patch immediately, with fully compromised systems at risk of data exfiltration and lateral movement to interconnected systems.
“The Centre for Cybersecurity Belgium strongly recommends installing updates for vulnerable devices with the highest priority after thorough testing.”
Organizations running Apache MINA in production should identify all instances calling IoBuffer.getObject() and verify whether patched versions are deployed. Given that the exploit requires low privileges and is remotely accessible, internet-facing applications using this library face the highest risk and should be prioritized. Security teams should also review logs for IoBuffer.getObject() invocations to detect potential pre-patch exploitation.
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What changed
The CCB published a critical vulnerability advisory for CVE-2026-41635 affecting Apache MINA, a network application framework. The vulnerability stems from an unvalidated code path in AbstractIoBuffer.resolveClass() that bypasses the classname allowlist, allowing arbitrary code execution when applications call IoBuffer.getObject(). The flaw carries a CVSS 3.1 score of 9.8 and is remotely exploitable without authentication.
Organizations using Apache MINA in any capacity should treat this as a priority remediation item given the CVSS critical severity rating. While patching to the latest version prevents future exploitation, organizations should also assess whether systems may have been compromised prior to patching, as the CCB notes that patching does not remediate historic compromise. Incident reporting is available through the CCB's reporting portal.
What to do next
- Patch vulnerable Apache MINA installations to the latest version immediately
- Upscale monitoring and detection capabilities to identify suspicious activity related to this vulnerability
Archived snapshot
Apr 28, 2026GovPing captured this document from the original source. If the source has since changed or been removed, this is the text as it existed at that time.
Warning: Critical arbitrary code execution vulnerability in Apache MINA, Patch Immediately!
Image
Published : 27/04/2026
- Last update: 27/04/2026
- Affected software: Apache MINA 2.0.0 <= 2.0.27, 2.1.0 <= 2.1.10, and 2.2.0 <= 2.2.5
- Type: Remote code execution
- CVE/CVSS → CVE-2026-41635: CVSS 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
Sources
Apache ZDRES-059 - https://lists.apache.org/thread/1l91w1mqsb3lwfd504fs045ylxntt2tm
Risks
Applications that use a vulnerable instance of Apache MINA are affected when calling the IoBuffer.getObject() function. Attackers will target these systems to gain arbitrary code execution on applications utilizing Apache MINA. This vulnerability requires low privileges and is remotely exploitable. Fully compromised systems can be used to exfiltrate data or attack other interconnected systems. A full compromise can have a high impact on the confidentiality, integrity and availability of the system.
Description
CVE-2026-41635 is an arbitrary code execution vulnerability in Apache MINA. The AbstractIoBuffer.resolveClass() method contains two branches, where one of them performs no class validation, bypassing the classname allowlist entirely. This results in arbitrary code execution. Systems affected are applications using Apache MINA that call the IoBuffer.getObject() method.
Recommended Actions
Patch
The Centre for Cybersecurity Belgium strongly recommends installing updates for vulnerable devices with the highest priority after thorough testing.
Monitor/Detect
The CCB recommends organizations upscale monitoring and detection capabilities to identify any related suspicious activity and ensure a swift response in case of an intrusion.
In case of an intrusion, you can report an incident via https://ccb.belgium.be/en/cert/report-incident.
While patching appliances or software to the newest version may protect against future exploitation, it does not remediate historic compromise.
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