CVE-2026-107726

Hazelcast allows arbitrary member memory access by low-privileged client

Workarounds

If you cannot update to a fixed version immediately, restrict cluster access to trusted clients only and ensure clients are hardened against compromise.

References

Security Advisory on the Hazelcast Support Portal

A flaw has been found in Hazelcast Enterprise Edition and Community Edition, which would allow a low-privileged malicious client to read arbitrary data in memory from any cluster member (including Java heap memory, off-heap data, and JVM process address space). Additionally, such a client may be able to cause one or more cluster members to crash, or in some Enterprise Edition configurations also corrupt memory contents, potentially leading to remote code execution. Both slim and full distributions are affected.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

Kodem intelligence

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Enterprise customers should upgrade to a fixed version of Hazelcast Enterprise Edition:

• 5.7.0
• 5.6.1
• 5.5.10
• 5.4.5

Customers with extended support contracts should contact Hazelcast Support for information on patches for older versions.

Community Edition users should upgrade to version 5.7.0.

Hazelcast also recommends all customers follow the advice in our Security Hardening guide, including:

• Ensure Hazelcast Security is enabled and client authorization is enforced.
• Define an explicit allowlist for zero config Compact serialization.
• Avoid deploying clients on internet-facing non-secure networks or non-secure hosts.
• Ensure your Hazelcast cluster is appropriately protected by firewall rules.
• Disable any features you are not using.

1. What is CVE-2026-107726? CVE-2026-107726 is a critical-severity improper input validation vulnerability in com.hazelcast:hazelcast (maven), affecting versions = 5.6.0. It is fixed in 5.7.0. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. Which versions of com.hazelcast:hazelcast are affected by CVE-2026-107726? com.hazelcast:hazelcast (maven) versions = 5.6.0 is affected.
3. Is there a fix for CVE-2026-107726? Yes. CVE-2026-107726 is fixed in 5.7.0. Upgrade to this version or later.
4. Is CVE-2026-107726 exploitable, and should I be worried? Whether CVE-2026-107726 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2026-107726 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2026-107726?
   • Upgrade com.hazelcast:hazelcast to 5.7.0 or later
   • Upgrade com.hazelcast:hazelcast to 5.7.0 or later
   • Upgrade com.hazelcast:hazelcast to 5.7.0 or later

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