Unsafe Deserialization in io.opentelemetry.javaagent:opentelemetry-javaagent (CVE-2026-33701)
Summary
Vulnerability in io.opentelemetry.javaagent:opentelemetry-javaagent (CVE-2026-33701). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 2.26.1 or later.
Original description
The description as published by the source.
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:
- OpenTelemetry Java instrumentation is attached as a Java agent (
-javaagent) - An RMI endpoint is network-reachable (e.g. JMX remote port, an RMI registry, or any application-exported RMI service)
- 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:
-Dotel.instrumentation.rmi.enabled=false
Credits
This vulnerability was responsibly disclosed in coordination with Datadog.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-33701 has been found in io.opentelemetry.javaagent:opentelemetry-javaagent.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: upgrade io.opentelemetry.javaagent:opentelemetry-javaagent to 2.26.1 or later.
If unsure, ask your IT team or search "io.opentelemetry.javaagent:opentelemetry-javaagent CVE-2026-33701" on the vendor's site.
CVE-2026-33701 (io.opentelemetry.javaagent:opentelemetry-javaagent) — CWE-502 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 2.26.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Unsafe deserialization (CWE-502) exists in io.opentelemetry.javaagent:opentelemetry-javaagent.
Check the vendor advisory for the affected versions of io.opentelemetry.javaagent:opentelemetry-javaagent.
Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.
Update to 2.26.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで io.opentelemetry.javaagent:opentelemetry-javaagent を使っているサービスとバージョンを洗い出す。
-
2Apply patch patch
Upgrade io.opentelemetry.javaagent:opentelemetry-javaagent to 2.26.1ステージング環境で 2.26.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web github.com
- web access.redhat.com
- web bugzilla.redhat.com
- web security.access.redhat.com
- web github.com