How severe is CVE-2026-33701?

No CVSS score has been assigned to CVE-2026-33701 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-33701?

CVE-2026-33701 affects the following packages: io.opentelemetry.javaagent:opentelemetry-javaagent (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-33701?

Update io.opentelemetry.javaagent:opentelemetry-javaagent to 2.26.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33701 is resolved across your whole dependency graph.

How do I detect CVE-2026-33701 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.opentelemetry.javaagent:opentelemetry-javaagent, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-33701 if there is no patch (or I can't update yet)?

Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Is CVE-2026-33701 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-33701 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-33701?

CVE-2026-33701 has an EPSS (Exploit Prediction Scoring System) score of 0.9%, placing it in the 61th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-33701?

CVE-2026-33701 is classified as Deserialization of Untrusted Data (CWE-502). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-33701 published, and has it been updated?

CVE-2026-33701 was published on March 27, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

Not in CISA KEV

CVE-2026-33701 — opentelemetry-javaagent

Fix: open-telemetry/opentelemetry-java-instrumentation@9cf4fba

CVE-2026-33701 is a Deserialization of Untrusted Data vulnerability in io.opentelemetry.javaagent:opentelemetry-javaagent. A fix is available for io.opentelemetry.javaagent:opentelemetry-javaagent — see the affected versions and patch details below.

OpenTelemetry: Unsafe Deserialization in RMI Instrumentation may Lead to Remote Code Execution

Also known asGHSA-xw7x-h9fj-p2c7

Published

Mar 27, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 3, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-33701.

EPSS Exploitation Probability

via FIRST.org ↗

0.9%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs61th percentile — riskier than 61% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

☕io.opentelemetry.javaagent:opentelemetry-javaagent

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`io.opentelemetry.javaagent:opentelemetry-javaagent`	all versions	2.26.1`io.opentelemetry.javaagent:opentelemetry-javaagent:2.26.1`

Affected Products

1 product · 1 configurations

Application

opentelemetry instrumentation for javalinuxfoundation

< 2.26.1

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.opentelemetry.javaagent:opentelemetry-javaagent, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.opentelemetry.javaagent:opentelemetry-javaagent to 2.26.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33701 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

Workaround published by Red Hat

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Source: Red Hat security advisory for CVE-2026-33701 (CC BY 4.0)

Frequently Asked Questions

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