CVE-2026-21999: Vulnerability in the XML Database component of Oracle Database Server

Routine

MEDIUM 5.3UPGRADE

CVE-2026-21999 is a medium-severity flaw (CVSS 5.3) affecting xml database. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Vulnerability in the XML Database component of Oracle Database Server. Supported versions that are affected are 23.4.0-23.26.1. Difficult to exploit vulnerability allows unauthenticated attacker with network access via HTTPS to compromise XML Database. Successful attacks require human interaction from a person other than the attacker. Successful attacks of this vulnerability can result in unauthorized access to critical data or complete access

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 85%)
CISA exploited list	No
Weakness	CWE-200
Published	2026-04-21
Last modified	2026-10-26

Publisher (CNA): Oracle · Vendor: oracle

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-21 21:16 UTCPublished CVE record published
2026-10-26 22:10 UTCUpdated Record last modified

oracle xml database UPGRADE

Affected: >= 23.4 and <= 23.26.1

Fixed in: newer than 23.26.1

Safe to downgrade to: a release before 23.4

1. Check installed version

apt-cache policy xml-database || rpm -q xml-database || xml-database --version

2. UPGRADE to newer than 23.26.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade xml-database

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade xml-database

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 23.4 (Debian / Ubuntu)

apt-cache madison xml-database sudo apt install xml-database=<VERSION_BEFORE_23.4> sudo apt-mark hold xml-database

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list xml-database sudo dnf downgrade xml-database-<VERSION_BEFORE_23.4> sudo dnf versionlock add xml-database

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-21999?

xml database: upgrade to newer than 23.26.1. Exact commands for each OS are on this page.

Is CVE-2026-21999 being exploited?

CVE-2026-21999 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-21999 affect?

CVE-2026-21999 affects xml database. Severity is medium (CVSS 5.3). Vulnerability in the XML Database component of Oracle Database Server. Supported versions that are affected are 23.4.0-23.26.1. Difficult to exploit vulnerability allows unauthenticated attacker with network access via HTTPS to compromise

How urgent is CVE-2026-21999?

Priority 22/100. No elevated risk signals yet.

Software pages

Oracle Database vulnerabilities

References

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