CVE-2026-33701: OpenTelemetry: Unsafe Deserialization in RMI Instrumentation may Lead to Remote Code Execution

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 io.opentelemetry.javaagent:opentelemetry-javaagent (Maven) < 2.26.1, fixed in 2.26.1. Check your lockfile, including transitive dependencies.

What it is

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

From the GitHub advisory

In versions prior to 2.26.1, the RMI instrumentation registered a custom endpoint that deserialized incoming data without applying serialization filters. 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: 1. OpenTelemetry Java instrumentation is attached as a Java agent (-javaagent) 2. An RMI endpoint is network-reachable (e.g. JMX remote port, an RMI registry, or any application-exported RMI service) 3. A gadget-chain-compatible library is present on the classpath

Impact Arbitrary remote code execution with the privileges of the user running the instrumented JVM.

Recommendation Upgrade to version 2.26.1 or later.

Workarounds Set the following system property to disable the RMI integration:

Credits This vulnerability was responsibly disclosed in coordination with Datadog.

Weakness type: CWE-502.

Product: io.opentelemetry.javaagent:opentelemetry-javaagent (Maven) · Assigned by: GitHub_M · Published: 2026-03-27

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• 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 yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 1.11% probability of exploitation activity in the next 30 days; percentile 66.

Timeline

• 2026-03-25 — GitHub-reviewed advisory GHSA-xw7x-h9fj-p2c7 published (critical)
• 2026-03-27 — CVE record published by GitHub_M
• 2026-08-17 — CVE record last updated

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-xw7x-h9fj-p2c7 github.com
2. CVE.org record CVE-2026-33701 cve.org
3. NVD entry CVE-2026-33701 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. access.redhat.com access.redhat.com
5. RHBZ#2452071 bugzilla.redhat.com
6. security.access.redhat.com security.access.redhat.com

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