CVE-2026-116486 easymock CVE debrief

Who should care

Defenders responsible for systems and applications using Objenesis should assess exposure and prioritize verification and remediation efforts. This includes reviewing and updating affected systems and dependencies, monitoring for potential ClassCastException failures, and tracking exceptions and retesting remediated assets. Security teams and vulnerability management teams should also be aware of the potential impacts of this vulnerability on their systems

Why it matters

Defenders should care about CVE-2026-116486 because it allows for type confusion in Objenesis before version 3.6, potentially leading to ClassCastException failures and object substitution across class loaders. Verification and remediation efforts should be prioritized for systems and applications using affected Objenesis versions.

• ClassCastException failures due to type confusion
• Potential for object substitution across class loaders
• Verification priority for Objenesis versions before 3.6

Technical summary

The Objenesis library before version 3.6 is vulnerable to type confusion due to instantiator caching based on class name. This allows an attacker to substitute objects of one class with objects of another class, potentially leading to ClassCastException failures. The vulnerability arises from Objenesis caching instantiators by class name, which can lead to type confusion when same-named classes are used across different class loaders. This issue can have significant implications for systems and applications using affected Objenesis versions.

Defensive priority

Defenders should prioritize verifying and upgrading to Objenesis version 3.6 or later to mitigate this vulnerability.

Recommended defensive actions

• Verify Objenesis version and upgrade to 3.6 or later if necessary
• Review and update affected systems and dependencies
• Monitor for potential ClassCastException failures
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability is caused by Objenesis caching instantiators by class name, leading to type confusion when same-named classes are used across different class loaders. This issue allows an attacker to substitute objects of one class with objects of another class, potentially leading to ClassCastException failures. The vulnerability is particularly concerning because it enables code in one class loader to substitute objects into another, which can have significant implications for systems and applications using affected Objenesis 3.6.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.