CVE-2026-33701: OpenTelemetry Java Instrumentation RCE via Unsafe Deserialization in RMI

CVE-2026-33701 · Severity: critical · CVSS 9.8 · Published 2026-03-27

OpenTelemetry Java instrumentation, a tool used to monitor application performance, contains a vulnerability in how it handles remote communication. If an application is monitored using this tool and has certain common libraries installed, an attacker could remotely execute malicious code on the server. This could lead to a full system takeover, data theft, or service disruption.

Technologies: io.opentelemetry.javaagent:opentelemetry-javaagent (Maven), Opentelemetry Java Instrumentation. Vendors: Linuxfoundation, Maven, Opentelemetry.

Quick answers

Is CVE-2026-33701 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-33701 being exploited in the wild.
How severe is CVE-2026-33701?
Critical severity, with a CVSS score of 9.8, published 27 March 2026.
Which products and versions are affected?
io.opentelemetry.javaagent:opentelemetry-javaagent (Maven) < 2.26.1, ECOSYSTEM:introduced=0,fixed=2.26.1; Opentelemetry Java Agent < 2.26.1; Opentelemetry Java Instrumentation < 2.26.1.
Is there a fix for CVE-2026-33701?
Yes. io.opentelemetry.javaagent:opentelemetry-javaagent (Maven): upgrade to 2.26.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-33701 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-33701?
Check whether you run Linuxfoundation Opentelemetry Instrumentation For Java, io.opentelemetry.javaagent:opentelemetry-javaagent (Maven), Opentelemetry Java Agent or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • io.opentelemetry.javaagent:opentelemetry-javaagent (Maven): upgrade to 2.26.1 or later
    # set io.opentelemetry.javaagent:opentelemetry-javaagent to 2.26.1 in your pom.xml or build.gradle

Technical details

An unsafe deserialization vulnerability exists in the RMI (Remote Method Invocation) instrumentation of the OpenTelemetry Java agent. The component registers a custom endpoint that processes incoming data without applying necessary serialization filters. An attacker can exploit this by sending a crafted malicious object to a reachable JMX or RMI port. Successful exploitation requires the Java agent to be active, a reachable RMI/JMX endpoint, and the presence of a gadget-chain-compatible library on the application's classpath. This allows for arbitrary code execution with the privileges of the JVM process. The issue is fixed in version 2.26.1.

Affected products

  • OpenTelemetry opentelemetry-javaagent < 2.26.1

Identifiers

  • CVE-2026-33701
  • GHSA-xw7x-h9fj-p2c7

Timeline

  • 2026-03-23: patched: Fix committed and version 2.26.1 released.
  • 2026-03-25: advisory: GitHub Advisory published.

References

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