GraalvmApplication · Oracle

CVE-2026-21945

HIGH · 7.5 CVSS v3.1 Published 2026-01-20

Mitigation only

No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.

See remediation →

84/100

Remediation priority · High

Remotely reachable No privileges Zero-click

Official description

NVD · unedited

Vulnerability in the Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: Security). Supported versions that are affected are Oracle Java SE: 8u471, 8u471-b50, 8u471-perf, 11.0.29, 17.0.17, 21.0.9, 25.0.1; Oracle GraalVM for JDK: 17.0.17 and 21.0.9; Oracle GraalVM Enterprise Edition: 21.3.16. Easily exploitable vulnerability allows unauthenticated attacker with network access via multiple protocols to compromise Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of Oracle Java SE, Oracle GraalVM for JDK, Oracle GraalVM Enterprise Edition. Note: This vulnerability applies to Java deployments, typically in clients running sandboxed Java Web Start applications or sandboxed Java applets, that load and run untrusted code (e.g., code that comes from the internet) and rely on the Java sandbox for security. This vulnerability does not apply to Java deployments, typically in servers, that load and run only trusted code (e.g., code installed by an administrator). CVSS 3.1 Base Score 7.5 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Technical summary

dbcve analysis · high confidence

This is a Denial of Service (DoS) vulnerability in the Security component of Oracle Java SE, Oracle GraalVM for JDK, and Oracle GraalVM Enterprise Edition. An unauthenticated remote attacker with network access can cause a hang or frequently repeatable crash (complete DOS) of affected Java deployments. The vulnerability specifically impacts sandboxed Java Web Start applications or sandboxed Java applets that load and run untrusted code from the internet.

MitigationApply the applicable Oracle security patch for the affected Java version (8u471+, 11.0.29+, 17.0.17+, 21.0.9+, or 25.0.1+). For deployments that do not require Java Web Start or applets, disable these components to reduce attack surface.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions

NVD · CPE data

GraalvmApplication

Affected:= 21.3.16

Graalvm For JdkApplication

Affected:= 17.0.17= 21.0.9

JdkApplication

Affected:= 1.8.0= 11.0.29= 17.0.17= 21.0.9= 25.0.1

JreApplication

Affected:= 1.8.0= 11.0.29= 17.0.17= 21.0.9= 25.0.1

CVSS breakdown

From the vector

Attack vector: Network
Complexity: Low
Privileges: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Identify installed Java version

Run 'java -version' or 'javac -version' from command line to get the exact version string. For Oracle JDK/JRE, also check the 'java -version' output for the vendor information (Oracle, GraalVM, etc.)

Affected if The version matches any of: Oracle JDK/JRE 1.8.0, 11.0.29, 17.0.17, 21.0.9, 25.0.1; Oracle GraalVM for JDK 17.0.17 or 21.0.9; Oracle GraalVM 21.3.16
Check if Java Web Start is in use

Look for JNLP (Java Network Launch Protocol) files on the system, check for javaws.exe process, or inspect browser configurations for Java Web Start plugin/enabled Java content in browsers

Affected if Java Web Start applications are deployed or accessible on the network, as the vulnerability is exploited through sandboxed Web Start apps loading untrusted code
Check if Java applets are in use

Search for .jar files referenced in HTML applet tags, check browser Java plugin settings, or look for legacy applet-based applications in the environment

Affected if Java applets are enabled or accessible, as the vulnerability is exploitable through applets loading untrusted code from the internet

You are affected if your environment runs any of the listed Oracle Java/GraalVM versions AND uses Java Web Start or applets that load untrusted code from the network.

Generated from the published advisory. Verify against your own configuration.

Remediation

dbcve · scoped

Mitigation available No clean upgrade yet — mitigate in the meantime

Mitigation

Apply the applicable Oracle security patch for the affected Java version (8u471+, 11.0.29+, 17.0.17+, 21.0.9+, or 25.0.1+). For deployments that do not require Java Web Start or applets, disable these components to reduce attack surface.

Recommended fix Moderate confidence

Latest available Oracle Java SE 8u, 11u, 17u, 21u, or 25u release (subsequent to affected versions)

Identify the currently installed Oracle Java SE or GraalVM version using 'java -version' or 'java --version'
Determine which affected version is in use (1.8.0, 11.0.29, 17.0.17, 21.0.9 for JDK/JRE, or 21.3.16 for GraalVM Enterprise Edition)
Download the latest available Oracle Java SE update from the official Oracle website or your Oracle support portal
Alternatively, for Red Hat Enterprise Linux systems, apply the latest security errata via 'yum update java-*' or 'yum update'
Verify the new version after installation using 'java -version'
For production systems, test application compatibility with the new Java version before deploying

Caveat Upgrading Java versions may introduce compatibility issues with existing applications; test thoroughly before production deployment

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Graalvm Scoped from the published advisory

Consultation2.0 h
Implementation4.0 h
Testing3.0 h
Review / QA1.0 h

10.0 hours of engineering $1,750

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Scan for this in your stack

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References

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-21945 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2026-21945?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

A fix existsA vendor remedy is published

Severity 7.5 High

Exploit likelihood EPSS, next 30 days 0.9%

Affects: Graalvm

Remediation

A high-priority fix

Fix this in Graalvm 10 hrs · Moderate

Typical engagement from $1,750

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2026-21945 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

Check your environment

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References