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CVE-2026-107726: Hazelcast: Arbitrary member memory access by low-privileged client

• Severity: critical (CVSS 9.3 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-08 · updated 2026-10-09
• Weakness: CWE-20

Description

Hazelcast is a unified real-time data platform combining stream processing with a fast data store. Prior to 5.4.5, 5.5.10, and 5.6.1, improper validation of data supplied by a malicious client able to connect to a cluster allows arbitrary reads from a cluster member's Java heap, off-heap data, and JVM process address space. The same flaw can crash cluster members and, in some Hazelcast Enterprise Edition configurations, corrupt memory with possible arbitrary code execution. Both slim and full distributions are affected. This issue is fixed in versions 5.4.5, 5.5.10, 5.6.1, and 5.7.0.

Affected products

• hazelcast: before 5.4.5; from 5.5.0, < 5.5.10; from 5.6.0, < 5.6.1

References

• https://docs.hazelcast.com/hazelcast/5.7/release-notes/community
• https://docs.hazelcast.com/hazelcast/5.7/release-notes/enterprise
• https://github.com/hazelcast/hazelcast/commit/361979da12f18950c24719db832ca6c5e7c0534f
• https://github.com/hazelcast/hazelcast/releases/tag/v5.7.0
• https://github.com/hazelcast/hazelcast/security/advisories/GHSA-6v25-8wq6-xq4j

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