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CVE-2023-21830: Vulnerability in the Oracle Java SE, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: S

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This month
MEDIUM 5.3REMOTEUPGRADEDOWNGRADEDOWNGRADE

CVE-2023-21830 is a medium-severity flaw (CVSS 5.3) affecting communications unified assurance, graalvm, jdk. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Vulnerability in the Oracle Java SE, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: Serialization). Supported versions that are affected are Oracle Java SE: 8u351, 8u351-perf; Oracle GraalVM Enterprise Edition: 20.3.8 and 21.3.4. Easily exploitable vulnerability allows unauthenticated attacker with network access via multiple protocols to compromise Oracle Java SE, Oracle GraalVM Enterprise Edition. Successful attacks

Why this priority

  • Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score5.3 (Medium)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance1.1% (top 35%)
CISA exploited listNo
Published2023-01-18
Last modified2026-06-17
Publisher (CNA): Oracle · Vendor: azul · oracle

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Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

oracle communications unified assurance UPGRADE
Affected: >= 5.5.0 and <= 5.5.17 · >= 6.0.0 and <= 6.0.2
Fixed in: newer than 6.0.2
Safe to downgrade to: a release before 5.5.0
1. Check installed version
apt-cache policy communications-unified-assurance || rpm -q communications-unified-assurance || communications-unified-assurance --version
2. UPGRADE to newer than 6.0.2 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade communications-unified-assurance
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade communications-unified-assurance
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 5.5.0 (Debian / Ubuntu)
apt-cache madison communications-unified-assurance sudo apt install communications-unified-assurance=<VERSION_BEFORE_5.5.0> sudo apt-mark hold communications-unified-assurance
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list communications-unified-assurance sudo dnf downgrade communications-unified-assurance-<VERSION_BEFORE_5.5.0> sudo dnf versionlock add communications-unified-assurance
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.
oracle graalvm DOWNGRADE
Affected: 20.3.8 · 21.3.4 · 22.3.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 20.3.8
1. Check installed version
apt-cache policy graalvm || rpm -q graalvm || graalvm --version
2. No fixed release: DOWNGRADE to a release before 20.3.8 (Debian / Ubuntu)
apt-cache madison graalvm sudo apt install graalvm=<VERSION_BEFORE_20.3.8> sudo apt-mark hold graalvm
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list graalvm sudo dnf downgrade graalvm-<VERSION_BEFORE_20.3.8> sudo dnf versionlock add graalvm
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.
oracle jdk DOWNGRADE
Affected: 1.8.0 update351 · 11.0.17 · 17.0.5 · 19.0.1
Fixed in: no fixed release known
Safe to downgrade to: a release before 1.8.0
1. Check installed version
apt-cache policy jdk || rpm -q jdk || jdk --version
2. No fixed release: DOWNGRADE to a release before 1.8.0 (Debian / Ubuntu)
apt-cache madison jdk sudo apt install jdk=<VERSION_BEFORE_1.8.0> sudo apt-mark hold jdk
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list jdk sudo dnf downgrade jdk-<VERSION_BEFORE_1.8.0> sudo dnf versionlock add jdk
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.
oracle jre DOWNGRADE
Affected: 1.8.0 update351 · 11.0.17 · 17.0.5 · 19.0.1
Fixed in: no fixed release known
Safe to downgrade to: a release before 1.8.0
1. Check installed version
apt-cache policy jre || rpm -q jre || jre --version
2. No fixed release: DOWNGRADE to a release before 1.8.0 (Debian / Ubuntu)
apt-cache madison jre sudo apt install jre=<VERSION_BEFORE_1.8.0> sudo apt-mark hold jre
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list jre sudo dnf downgrade jre-<VERSION_BEFORE_1.8.0> sudo dnf versionlock add jre
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.
azul zulu DOWNGRADE
Affected: 6.51 · 7.57 · 8.66
Fixed in: no fixed release known
Safe to downgrade to: a release before 6.51
1. Check installed version
apt-cache policy zulu || rpm -q zulu || zulu --version
2. No fixed release: DOWNGRADE to a release before 6.51 (Debian / Ubuntu)
apt-cache madison zulu sudo apt install zulu=<VERSION_BEFORE_6.51> sudo apt-mark hold zulu
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list zulu sudo dnf downgrade zulu-<VERSION_BEFORE_6.51> sudo dnf versionlock add zulu
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-2023-21830?

communications unified assurance: upgrade to newer than 6.0.2; graalvm: downgrade or apply the listed mitigation; jdk: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-21830 being exploited?

CVE-2023-21830 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-2023-21830 affect?

CVE-2023-21830 affects communications unified assurance, graalvm, jdk. Severity is medium (CVSS 5.3). Vulnerability in the Oracle Java SE, Oracle GraalVM Enterprise Edition product of Oracle Java SE (component: Serialization). Supported versions that are affected are Oracle Java SE: 8u351, 8u351-perf; Oracle GraalVM Enterprise Edition: 20.

How urgent is CVE-2023-21830?

Priority 40/100. Remotely exploitable, no login, no user action

Software pages

Java vulnerabilities

References

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