CVE-2026-21933Network attack vector

Unauthenticated data disclosure and modification

Published Jan 20, 2026 · Updated Jan 20, 2026

A networking flaw in affected Oracle Java SE and GraalVM releases allows remote attackers to read and modify some accessible data. Oracle identifies Networking APIs, including calls supplied through web services, but has not disclosed the flawed API, input, or incorrect operation. Exploitation requires user interaction when untrusted network data reaches those APIs or sandboxed client code runs.

CVSS severity6.1
Medium
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

A networking flaw in affected Oracle Java SE and GraalVM releases allows remote attackers to read and modify some accessible data. Oracle identifies Networking APIs, including calls supplied through web services, but has not disclosed the flawed API, input, or incorrect operation. Exploitation requires user interaction when untrusted network data reaches those APIs or sandboxed client code runs.

The record

CVE
CVE-2026-21933
Published
Jan 20, 2026
Updated
Jan 20, 2026
Vendor
Oracle
Product
Oracle GraalVM Enterprise Edition
Classifications
T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=21.3.16

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Oracle · Oracle GraalVM Enterprise Editionversion=21.3.16
Oracle · Oracle GraalVM for JDKversion=17.0.17; version=21.0.9
Oracle · Java Platform, Standard Edition (Java SE)version=11.0.29; version=17.0.17; version=21.0.9; version=25.0.1; version=8u471; version=8u471-b50; version=8u471-perf

Published CVSS scores

6.1OracleCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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.

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

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo