CVE-2021-28167Public exploitNetwork attack vector

Security bypass via premature constant-pool resolution

Published Apr 21, 2021 · Updated Aug 3, 2024

Missing initialization in Eclipse OpenJ9 0.25.0 and earlier allows remote attackers to access static members through ConstantPool API use. The jdk.internal.reflect.ConstantPool API pre-resolves certain entries, allowing static methods or members to be used before the class initialization method runs. Reachability requires attacker-controlled Java behavior to invoke this internal API, and the result is observation or use of uninitialized static state.

CVSS severity6.5
Medium
EPSS probability1.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing initialization in Eclipse OpenJ9 0.25.0 and earlier allows remote attackers to access static members through ConstantPool API use. The jdk.internal.reflect.ConstantPool API pre-resolves certain entries, allowing static methods or members to be used before the class initialization method runs. Reachability requires attacker-controlled Java behavior to invoke this internal API, and the result is observation or use of uninitialized static state.

The record

CVE
CVE-2021-28167
Published
Apr 21, 2021
Updated
Aug 3, 2024
Vendor
The Eclipse Foundation
Product
Eclipse OpenJ9
Classifications
CWE-909
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 21, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=unspecified <=0.25.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Eclipse Foundation · Eclipse OpenJ9version=unspecified <=0.25.0

Published CVSS scores

6.4NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

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-909Missing Initialization of Resource

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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