CVE-2026-6918Public exploitNetwork attack vector

Remote JITServer crash via unchecked message size

Published May 5, 2026 · Updated May 5, 2026

Out-of-bounds read in Eclipse OpenJ9 0.21 through 0.58 allows remote attackers to crash JITServer with a crafted TCP message. Message::deserialize trusts DataDescriptor._size, and MessageBuffer::readData advances its cursor past the received buffer without a bounds check. Any network client can reach the flaw when JITServer runs without TLS client authentication, the default, causing a segmentation fault and loss of JIT compilation service.

CVSS severity8.7
High
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Eclipse OpenJ9 0.21 through 0.58 allows remote attackers to crash JITServer with a crafted TCP message. Message::deserialize trusts DataDescriptor._size, and MessageBuffer::readData advances its cursor past the received buffer without a bounds check. Any network client can reach the flaw when JITServer runs without TLS client authentication, the default, causing a segmentation fault and loss of JIT compilation service.

The record

CVE
CVE-2026-6918
Published
May 5, 2026
Updated
May 5, 2026
Vendor
The Eclipse Foundation
Product
Eclipse OpenJ9
Classifications
CWE-125, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 5, 2026CVE publishedPublication date reported by the CVE source.
  2. May 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.21 <0.59

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Eclipse Foundation · Eclipse OpenJ9version=0.21 <0.59

Published CVSS scores

8.7Eclipse FoundationCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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