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CRITICAL severity

CVE-2026-42779 — mina-core

CRITICAL

CVE-2026-42779 is a critical-severity (CVSS 9.8) Deserialization of Untrusted Data vulnerability in org.apache.mina:mina-core. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for org.apache.mina:mina-core — see the affected versions and patch details below.

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

Also known asGHSA-vf5j-865m-mq7c
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
1 known
Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • A successful exploit gives an attacker total control of the affected component, not partial access.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-42779.

EPSS Exploitation Probability

via FIRST.org ↗
1.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs69th percentile — riskier than 69% of all scored CVEsHighest risk
0.00%0.58%1.15%1.73%0.0%1.2%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected
☕org.apache.mina:mina-core☕org.apache.mina:mina-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

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

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.apache.mina:mina-core≥ 2.1.0&&< 2.1.122.1.12org.apache.mina:mina-core:2.1.12
☕Mavenorg.apache.mina:mina-core≥ 2.2.0&&< 2.2.72.2.7org.apache.mina:mina-core:2.2.7

Affected Products

1 product · 2 configurations
Application
minaapache
≥ 2.2.0 && < 2.2.7
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

dinosn/CVE-2026-42779

CVE-2026-42779: Apache MINA AbstractIoBuffer.resolveClass() deserializat

⭐ 11🍴 2May 2026

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.mina:mina-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.apache.mina:mina-core to 2.1.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42779 is resolved across your whole dependency graph.

  3. Workarounds

    Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatLow

Red Hat products are affected by this vulnerability. However, the vulnerable code cannot be reached and therefore are not vulnerable. Due to this reason, this flaw has been rated with a low severity.

ProductFixed inAdvisory
OpenShift Developer Tools and Services 4.12ocp-tools-4/jenkins-rhel8:1786628667RHSA-2026:60247
OpenShift Developer Tools and Services 4.13ocp-tools-4/jenkins-rhel8:1786628681RHSA-2026:60249
OpenShift Developer Tools and Services 4.14ocp-tools-4/jenkins-rhel8:1786533561RHSA-2026:60248
OpenShift Developer Tools and Services 4.15ocp-tools-4/jenkins-rhel8:1786533565RHSA-2026:60239
OpenShift Developer Tools and Services 4.16ocp-tools-4/jenkins-rhel9:1787125166RHSA-2026:60251
OpenShift Developer Tools and Services 4.17ocp-tools-4/jenkins-rhel9:1787124635RHSA-2026:60246
OpenShift Developer Tools and Services 4.18ocp-tools-4/jenkins-rhel9:1787125069RHSA-2026:60250
OpenShift Developer Tools and Services 4.19ocp-tools-4/jenkins-rhel9:1787124632RHSA-2026:60252

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

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CVE-2026-42779: mina-core RCE — Fixed in 2.1.12