CVE-2023-21939Network attack vector

Data modification via Swing HTML object tags

Published Apr 18, 2023 · Updated Feb 13, 2025

Improper input validation in Swing in Oracle Java SE 8u361, 8u361-perf, 11.0.18, 17.0.6, and 20 allows remote attackers to modify data. The Swing HTML renderer recognizes untrusted object tags and creates java.awt.Component subclasses while rendering text instead of rejecting those elements. Exploitation requires a sandboxed applet or Web Start application that runs untrusted code, or an application such as a web service that passes attacker-controlled data to Swing APIs.

CVSS severity5.3
Medium
EPSS probability2.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Swing in Oracle Java SE 8u361, 8u361-perf, 11.0.18, 17.0.6, and 20 allows remote attackers to modify data. The Swing HTML renderer recognizes untrusted object tags and creates java.awt.Component subclasses while rendering text instead of rejecting those elements. Exploitation requires a sandboxed applet or Web Start application that runs untrusted code, or an application such as a web service that passes attacker-controlled data to Swing APIs.

The record

CVE
CVE-2023-21939
Published
Apr 18, 2023
Updated
Feb 13, 2025
Vendor
Oracle Corporation
Product
Java Platform, Standard Edition (Java SE)
Classifications
T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 18, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record 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=Oracle GraalVM Enterprise Edition:20.3.9
  2. Affected versionversion=Oracle GraalVM Enterprise Edition:21.3.5
  3. Affected versionversion=Oracle GraalVM Enterprise Edition:22.3.1
  4. Affected versionversion=Oracle Java SE:11.0.18
  5. Affected versionversion=Oracle Java SE:17.0.6
  6. Affected versionversion=Oracle Java SE:20
  7. Affected versionversion=Oracle Java SE:8u361
  8. Affected versionversion=Oracle Java SE:8u361-perf

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Oracle Corporation · Java Platform, Standard Edition (Java SE)version=Oracle GraalVM Enterprise Edition:20.3.9; version=Oracle GraalVM Enterprise Edition:21.3.5; version=Oracle GraalVM Enterprise Edition:22.3.1; version=Oracle Java SE:11.0.18; version=Oracle Java SE:17.0.6; version=Oracle Java SE:20; version=Oracle Java SE:8u361; version=Oracle Java SE:8u361-perf

Published CVSS scores

5.3Oracle CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitUnconfirmed

Weakness, pattern, technique

T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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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