CVE-2026-33701 OpenTelemetry: Unsafe Deserialization in RMI Instrumentation may Lead to Remote Code Execution
An attacker with network access to a configured JMX/RMI port on a Java 16 or earlier JVM using OpenTelemetry instrumentation can achieve remote code execution via unsafe deserialization.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33701?
CVE-2026-33701 is a critical unsafe deserialization vulnerability in open-telemetry opentelemetry-java-instrumentation, published on 27 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
OpenTelemetry Java Instrumentation provides OpenTelemetry auto-instrumentation and instrumentation libraries for Java. In versions prior to 2.26.1, the RMI instrumentation registered a custom endpoint that deserialized incoming data without applying serialization filters. On JDK version 16 and earlier, an attacker with network access to a JMX or RMI port on an instrumented JVM could exploit this to potentially achieve remote code execution. All three of the following conditions must be true to exploit this vulnerability: First, OpenTelemetry Java instrumentation is attached as a Java agent (`-javaagent`) on Java 16 or earlier. Second, JMX/RMI port has been explicitly configured via `-Dcom.sun.management.jmxremote.port` and is network-reachable. Third, gadget-chain-compatible library is present on the classpath. This results in arbitrary remote code execution with the privileges of the user running the instrumented JVM. For JDK >= 17, no action is required, but upgrading is strongly encouraged. For JDK < 17, upgrade to version 2.26.1 or later. As a workaround, set the system property `-Dotel.instrumentation.rmi.enabled=false` to disable the RMI integration.
Weakness: CWE-502
Which versions are affected by CVE-2026-33701?
2 open source packages ship an affected version, including io.opentelemetry.javaagent:opentelemetry-javaagent. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
io.opentelemetry.javaagent:opentelemetry-javaagent Maven | All versions | 2.26.1 |
io.opentelemetry.javaagent:opentelemetry-javaagent Maven | All versions | 2.26.1 |
Products include Linuxfoundation Opentelemetry Instrumentation for Java.
How do I fix CVE-2026-33701?
Upgrade io.opentelemetry.javaagent:opentelemetry-javaagent to 2.26.1 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-33701 being exploited?
There is no known exploitation of CVE-2026-33701 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in open-telemetry opentelemetry-java-instrumentation
Sources
Also known as GHSA-xw7x-h9fj-p2c7, ROOT-APP-MAVEN-CVE-2026-33701.