Cyber Resilience

CVE-2026-6918

Memory Safety in Eclipse Openj9 0.21.0 – 0.59.0

Public PoCMemory Safety
Published
05 May 2026
Modified
15 July 2026
Patch / advisory
View advisory
CVSS Score v4 8.7
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0052 41th percentile
Risk Priority 45 floored blend · peak EPSS

Summary

CVE-2026-6918 is a high-severity Out-of-bounds Read (CWE-125) vulnerability in Eclipse Openj9. Its CVSS base score is 8.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 41th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-6918 is a denial-of-service vulnerability (CWE-125: Out-of-bounds Read) affecting Eclipse Openj9 versions 0.21 through 0.58. It enables a pre-authentication remote attacker to crash the JITServer component by sending a specifically crafted 32-byte TCP message. The vulnerability received a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), reflecting high severity due to its network accessibility, low attack complexity, lack of privileges or user interaction required, and significant availability impact.

An unauthenticated attacker with network access to a vulnerable JITServer instance can exploit this issue remotely and pre-authentication. By transmitting the 32-byte crafted TCP message, the attacker triggers a crash of the JITServer, resulting in denial of service without impacting confidentiality or integrity.

Mitigation details and patches are documented in the Eclipse Openj9 security advisory at https://github.com/eclipse-openj9/openj9/security/advisories/GHSA-q393-vr4c-969r and pull request https://github.com/eclipse-openj9/openj9/pull/23793. Security practitioners should review these resources for upgrading to patched versions beyond 0.58.

EU & UK References

Vulnerability Data

In Eclipse Open9J versions 0.21 to 0.58, a pre-authentication remote attacker can crash JITServer by sending a 32-byte crafted TCP message.

CWE(s)
CWE-125CWE-1286

Related Threats

MITRE ATT&CK Enterprise Techniques

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1211 Exploitation for Stealth Stealth
Adversaries may exploit vulnerabilities to evade detection by hiding activity, suppressing logging, or operating within trusted or unmonitored components.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-2597Same product: Eclipse Openj9
CVE-2024-3933Same product: Eclipse Openj9
CVE-2025-4447Same product: Eclipse Openj9
CVE-2026-16439Same product: Eclipse Openj9
CVE-2024-10917Same product: Eclipse Openj9
CVE-2023-5676Same product: Eclipse Openj9
CVE-2025-55085Same vendor: Eclipse
CVE-2025-55082Same vendor: Eclipse
CVE-2026-16243Same vendor: Eclipse
CVE-2025-55100Same vendor: Eclipse

Affected Assets

eclipse
openj9
0.21.0 — 0.59.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.1.1
  • V1.4.2
  • V2.1.1
  • V2.2.2

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation directly finds out-of-bounds read flaws through static analysis, fuzzing, and dynamic bounds checks.

SI-10 Information Input Validation good match

SI-10 requires validation of information inputs for correctness, directly stopping syntactic validation failures from being introduced or exploitable.

SA-8 Security and Privacy Engineering Principles partial match

Secure engineering principles require bounds checking and memory-safe constructs that stop out-of-bounds reads from being introduced.

SC-39 Process Isolation partial match

Process isolation confines the effects of an out-of-bounds read to the compromised process.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure-development practices such as bounds checking and memory-safe languages directly prevent out-of-bounds reads.

ID.RA-01 partial match
prevents

Vulnerability scanning and recording can discover instances of out-of-bounds reads after code is deployed.

PR.PS-02 partial match
prevents

Routine patching replaces vulnerable code containing out-of-bounds read flaws.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development and acceptance includes fuzzing and static analysis that detect out-of-bounds read defects before release.

A.8.15 Logging partial match
finds

Logging can record evidence of an out-of-bounds read but does not prevent the weakness itself.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates input validation and bounds checking that directly prevent out-of-bounds reads.

A.8.26 Application security requirements partial match
prevents

Application security requirements include explicit bounds and memory-safety specifications that mitigate buffer over-reads.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure system architecture and engineering principles require memory-safe design patterns and runtime protections against out-of-bounds access.

A.8.28 Secure coding partial match
prevents

Secure coding standards explicitly forbid unsafe pointer arithmetic and mandate bounds-checked reads, eliminating CWE-125.

References