CVE-2026-89139: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-w8cx-4cf2-9hvr
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CWE-78
Published
Advisory Summary

CVE-2026-89139 is a HIGH security vulnerability vulnerability (CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product constructs all or part of an os command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended os command when it is sent to a downstream component.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-89139 at a Glance

CVE Identifier CVE-2026-89139
GHSA Identifier GHSA-w8cx-4cf2-9hvr
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-89139

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-89139, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'), where the product constructs all or part of an os command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended os command when it is sent to a downstream component. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

Temporal Server compiles a Worker Controller Instance module into its Worker Service, and that module registers a compute provider named subprocess whose function is to launch a worker by running a command on the machine hosting the Worker Service. The program name and the argument vector that provider executes are taken from the compute provider configuration supplied in the caller's request rather than from operator configuration. An authenticated caller holding only a write role in a single namespace can therefore configure a worker deployment version so that the Worker Service executes a command of the caller's choosing on its own host, under the account the server process runs as. Execution is immediate rather than deferred: the configuration handler invokes every provider using the invoke strategy directly after validating the submitted specification, so no scaling decision, task arrival, or unusual request sequence is required. Because the Worker Service process holds the persistence credentials for every namespace in the cluster and the cluster's TLS material, the consequence reaches beyond the caller's namespace to the cluster as a whole. The provider is present in the official temporal-server binaries and container images for the affected releases. The only control that can keep it unreachable is the compute provider allowlist, the per-namespace dynamic configuration setting workercontroller.compute_providers.enabled, and that control does not deny by default: its default value is an unset list, and the allowlist check is skipped entirely when the value is unset, so every registered compute provider is permitted, this one included. To determine whether a deployment is affected, check the following together. The deployed Temporal Server version is 1.31.0 or later and earlier than 1.31.3. The Worker Service is running, which it is in the default service set and therefore in a stock deployment. The effective per-namespace value of workercontroller.compute_providers.enabled is either unset or contains subprocess. And authorization is configured, meaning a real authorizer and claim mapper are in place; a deployment running with no authorizer already grants every caller unrestricted access to every namespace, so it has no namespace boundary for this to cross. Note that the separate per-namespace dynamic configuration setting workercontroller.enabled does not gate the affected path. It defaults to false, and a deployment that has never set it in any namespace is still affected, which was confirmed by running an affected release with no value for that setting present anywhere in dynamic configuration. To look for a compute configuration that is already attached, call DescribeWorkerDeploymentVersion for each worker deployment version in each namespace and check whether any scaling group's compute provider type is subprocess.

References

NVD — CVE-2026-89139 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-89139
Software Source Repository REPOSITORY
https://github.com/temporalio/temporal-auto-scaled-workers/pull/129
Software Source Repository REPOSITORY
https://github.com/temporalio/temporal/pull/12021
Software Release RELEASE
https://github.com/temporalio/temporal/releases/tag/v1.31.3
Software Release RELEASE
https://github.com/temporalio/temporal/releases/tag/v1.32.0

Frequently Asked Questions

What is CVE-2026-89139?
CVE-2026-89139 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection').
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-89139?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What CWE is associated with CVE-2026-89139?
CVE-2026-89139 is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') (The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.).
How can I check Maven dependencies for CVE-2026-89139?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-w8cx-4cf2-9hvr",
  "modified" : "2026-09-21T12:32:39Z",
  "published" : "2026-09-21T12:32:39Z",
  "aliases" : [ "CVE-2026-89139" ],
  "details" : "Temporal Server compiles a Worker Controller Instance module into its Worker Service, and that module registers a compute provider named subprocess whose function is to launch a worker by running a command on the machine hosting the Worker Service. The program name and the argument vector that provider executes are taken from the compute provider configuration supplied in the caller's request rather than from operator configuration. An authenticated caller holding only a write role in a single namespace can therefore configure a worker deployment version so that the Worker Service executes a command of the caller's choosing on its own host, under the account the server process runs as. Execution is immediate rather than deferred: the configuration handler invokes every provider using the invoke strategy directly after validating the submitted specification, so no scaling decision, task arrival, or unusual request sequence is required. Because the Worker Service process holds the persistence credentials for every namespace in the cluster and the cluster's TLS material, the consequence reaches beyond the caller's namespace to the cluster as a whole. The provider is present in the official temporal-server binaries and container images for the affected releases. The only control that can keep it unreachable is the compute provider allowlist, the per-namespace dynamic configuration setting workercontroller.compute_providers.enabled, and that control does not deny by default: its default value is an unset list, and the allowlist check is skipped entirely when the value is unset, so every registered compute provider is permitted, this one included. To determine whether a deployment is affected, check the following together. The deployed Temporal Server version is 1.31.0 or later and earlier than 1.31.3. The Worker Service is running, which it is in the default service set and therefore in a stock deployment. The effective per-namespace value of workercontroller.compute_providers.enabled is either unset or contains subprocess. And authorization is configured, meaning a real authorizer and claim mapper are in place; a deployment running with no authorizer already grants every caller unrestricted access to every namespace, so it has no namespace boundary for this to cross. Note that the separate per-namespace dynamic configuration setting workercontroller.enabled does not gate the affected path. It defaults to false, and a deployment that has never set it in any namespace is still affected, which was confirmed by running an affected release with no value for that setting present anywhere in dynamic configuration. To look for a compute configuration that is already attached, call DescribeWorkerDeploymentVersion for each worker deployment version in each namespace and check whether any scaling group's compute provider type is subprocess.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-89139"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/temporalio/temporal-auto-scaled-workers/pull/129"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/temporalio/temporal/pull/12021"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/temporalio/temporal/releases/tag/v1.31.3"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/temporalio/temporal/releases/tag/v1.32.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-78" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-21T12:17:24Z"
  }
}