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CVE-2026-21999 Oracle Corporation CVE debrief

A medium-severity vulnerability, CVE-2026-21999, was found in the XML Database component of Oracle Database Server. The vulnerability is difficult to exploit and allows an unauthenticated attacker with network access via HTTPS to compromise XML Database. Successful attacks require human interaction and can result in unauthorized access to critical data or complete access to all XML Database accessible data. The vulnerability has a CVSS 3.1 Base Score of 5.3 and is classified as medium severity.

Vendor
Oracle Corporation
Product
Oracle Database Server
CVSS
MEDIUM 5.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-21
Original CVE updated
2026-07-08
Advisory published
2026-04-21
Advisory updated
2026-07-08

Who should care

Organizations using Oracle Database Server versions 23.4.0-23.26.1 should prioritize patching this vulnerability to prevent potential data breaches. This is a medium-severity vulnerability that allows an unauthenticated attacker with network access via HTTPS to compromise XML Database, requiring human interaction for successful attacks.

Technical summary

CVE-2026-21999 is a vulnerability in the XML Database component of Oracle Database Server, affecting versions 23.4.0-23.26.1. The vulnerability has a CVSS 3.1 Base Score of 5.3 and is classified as medium severity. It allows an unauthenticated attacker with network access via HTTPS to compromise XML Database, requiring human interaction for successful attacks. The vulnerability can result in unauthorized access to critical data or complete access to all XML Database accessible data.

Defensive priority

Medium priority should be given to patching this vulnerability, as it can lead to unauthorized data access.

Recommended defensive actions

  • Apply the patch provided by Oracle as soon as possible
  • Review and update inventory of Oracle Database Server instances
  • Implement compensating controls to monitor and detect potential attacks
  • Verify and enforce HTTPS access controls
  • Educate users on the importance of human interaction in preventing successful attacks
  • Review relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record was published on 2026-04-21T21:16:25.060Z and last modified on 2026-07-08T03:27:15.830Z. The NVD entry is currently Analyzed. The evidence for this CVE is based on the official CVE record and NVD detail page. The vulnerability affects Oracle Database Server versions 23.4.0-23.26.1. The CVE record and NVD entry provide details on the vulnerability, its severity, and potential impact.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-21999 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-21999

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-21999 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-21999

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.