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VulnerabilityPublished Updated

CVE-2026-33701: open-telemetry opentelemetry-java-instrumentation · Deserialization of Untrusted Data

Affects open-telemetry opentelemetry-java-instrumentationSource CVE Database V5

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Not known to be exploited · CVSS 9.3 Critical : upgrade to 2.26.1 as a priority.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score
9.3Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.9% chance of exploitation in 30 days – higher than 60% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.26.1
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade opentelemetry-java-instrumentation and io.opentelemetry/opentelemetry-java-instrumentation to 2.26.1.

Affected software

ProductAffectedFixed in
open-telemetryopentelemetry-java-instrumentationAffected
  • <2.26.1
Fixed in
  • 2.26.1
Mavenio.opentelemetry/opentelemetry-java-instrumentationpkg:maven/io.opentelemetry/opentelemetry-java-instrumentationOther threatsAffected
  • <2.26.1
Fixed in
  • 2.26.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade OpenTelemetry Java Instrumentation to version 2.26.1 or later. If upgrading is not immediately possible and the JVM runs JDK 16 or earlier, disable the RMI instrumentation by setting the system property '-Dotel.instrumentation.rmi.enabled=false'. For JDK 17 and later, no action is required but upgrading is recommended. Red Hat notes that no other mitigations meeting their criteria are currently available.

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.

References

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