CVE-2026-46495: OpenDJ Pre-Auth RCE via Java Deserialization in JMX RMI

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 1.1%, percentile 66: FIRST’s model estimates a 1.1% chance of exploitation activity in the next 30 days, higher than 66% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes org.openidentityplatform.opendj:opendj-server-legacy (Maven) <= 5.1.0, fixed in 5.1.1. Check your lockfile, including transitive dependencies.

What it is

OpenDJ is an LDAPv3 compliant directory service. Prior to 5.1.1, the JMX RMI connector in opendj-server-legacy/src/main/java/org/opends/server/protocols/jmx/RmiConnector.java processes attacker-controlled credential objects before authentication without a restrictive jmx.remote.rmi.server.credentials.filter.pattern, and RmiAuthenticator.authenticate in opendj-server-legacy/src/main/java/org/opends/server/protocols/jmx/RmiAuthenticator.java accepts an unconstrained Object array rather than a two-element String[]. When the JMX Connection Handler is enabled and its TCP listener is reachable, an unauthenticated remote attacker can submit a crafted serialized Java object and achieve code execution in the OpenDJ server process. The handler is disabled by default, and successful exploitation depends on the runtime classpath and Java version; remote code execution was demonstrated against OpenDJ 4.4.15 on JDK 11 with Jackson 2.12.6.1. This issue is fixed in 5.1.1.

From the GitHub advisory

Summary

Description

A Deserialization of Untrusted Data (CWE-502) issue in OpenDJ's JMX RMI connector allows an unauthenticated remote attacker to deserialize arbitrary Java objects on the server. The vulnerability exists because the platform reads and processes attacker-controlled bytes prior to authentication. This affects OpenDJ Community Edition through 5.1.0. This has been patched in version 5.1.1.

Impact This impacts all current OpenDJ releases where the JMX Connection Handler is enabled. While disabled by default, it is frequently enabled in practice for monitoring integrations. Exploitation requires TCP reachability to the configured listener and does not require authentication, prior privileges, or client certificates. Successful exploitation results in unauthenticated Remote Code Execution (RCE), with the severity depending on the runtime classpath and Java version. Unauthenticated RCE was demonstrated on the OpenDJ 4.4.15 (JDK 11 + Jackson 2.12.6.1).

Patch This has been patched in OpenDJ Community Edition version 5.1.1. Users are encouraged to update to the latest release.

Weakness type: CWE-502.

Product: org.openidentityplatform.opendj:opendj-server-legacy (Maven) · Assigned by: GitHub_M · Published: 2026-09-15

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: present (depends on deployment conditions)
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 1.13% probability of exploitation activity in the next 30 days; percentile 66.

Timeline

• 2026-06-22 — GitHub-reviewed advisory GHSA-43x2-g84q-fmqx published (critical)
• 2026-09-15 — CVE record last updated
• 2026-09-15 — CVE record published by GitHub_M

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-43x2-g84q-fmqx github.com
2. CVE.org record CVE-2026-46495 cve.org
3. NVD entry CVE-2026-46495 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com
5. github.com github.com

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