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CVE-2026-6918 Eclipse Foundation CVE debrief

CVE-2026-6918 is a high-severity vulnerability 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. This issue has been publicly disclosed and has a CVSS score of 8.7. The vulnerability affects Eclipse Open9J versions between 0.21.0 and 0.59.0. Users of affected versions should apply patches or mitigations provided by the vendor. The CVE record and NVD details provide further information on this vulnerability.

Vendor
Eclipse Foundation
Product
Eclipse OpenJ9
CVSS
HIGH 8.7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-05
Original CVE updated
2026-07-15
Advisory published
2026-05-05
Advisory updated
2026-07-15

Who should care

Users of Eclipse Open9J versions 0.21 to 0.58 should prioritize patching or mitigating this vulnerability. Organizations relying on Eclipse Open9J for their applications or services are at risk if they haven't updated to a secure version. Security teams and IT administrators responsible for maintaining software dependencies should assess the risk and apply necessary patches or compensating controls.

Technical summary

CVE-2026-6918 is a remote denial-of-service (DoS) vulnerability in the JITServer component of Eclipse Open9J. An unauthenticated attacker can send a specially crafted 32-byte TCP message to cause a crash. The vulnerability is rated with a CVSS score of 8.7, indicating high severity. It is classified under CWE-125 (Out-of-bounds Read) and CWE-1286 (Improper Validation of User-Provided Data for Integrity). Affected versions include Eclipse Open9J from 0.21.0 up to but not including 0.59.0.

Defensive priority

High priority should be given to patching or mitigating CVE-2026-6918, especially for organizations using Eclipse Open9J in production environments. Immediate action is recommended to prevent potential disruptions or exploitation attempts.

Recommended defensive actions

  • Apply patches or updates provided by Eclipse for Open9J versions 0.21 to 0.58.
  • Implement network filters or firewalls to restrict access to JITServer if possible.
  • Monitor for unusual traffic patterns or server crashes indicative of exploitation attempts.
  • Inventory and assess the use of affected Open9J versions within the organization.
  • Consider compensating controls such as rate limiting for TCP traffic to JITServer.

Evidence notes

The CVE record and NVD details provide information on this vulnerability. Additional references include vendor advisories and issue tracking links. The vulnerability has been publicly disclosed and has a CVSS score of 8.7, indicating high severity.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-6918 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-6918

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-6918 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-6918

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://github.com/eclipse-openj9/openj9/pull/23793

    [email protected] - Issue Tracking, Patch

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://github.com/eclipse-openj9/openj9/security/advisories/GHSA-q393-vr4c-969r

    [email protected] - Exploit, Vendor Advisory

  • Source reference

    Unverified legacy reference

    URL: https://access.redhat.com/errata/RHSA-2026:22328

    0b0ca135-0b70-47e7-9f44-1890c2a1c46c

  • Source reference

    Unverified legacy reference

    URL: https://access.redhat.com/security/cve/CVE-2026-6918

    0b0ca135-0b70-47e7-9f44-1890c2a1c46c

  • Source reference

    Unverified legacy reference

    URL: https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6918.json

    0b0ca135-0b70-47e7-9f44-1890c2a1c46c

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.