CVE-2026-2611: MLflow Improper Origin Validation Vulnerability

CRITICAL
Advisory Identifier: GHSA-67c5-x5mf-rppq
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CVSS 9.6
CWE-940 CWE-346
Published
Advisory Summary

CVE-2026-2611 is a CRITICAL (CVSS 9.6) improper origin validation vulnerability (CWE-940: Improper Verification of Source of a Communication Channel) affecting MLflow libraries in the PyPI ecosystem. The issue involves improper origin validation in mlflow assistant /ajax-api endpoints enables browser-mediated local command execution. Remediation is available by upgrading affected packages to version 3.10.0.

CVE-2026-2611 at a Glance

CVE Identifier CVE-2026-2611
GHSA Identifier GHSA-67c5-x5mf-rppq
Severity CRITICAL
CVSS v3.1 Base Score 9.6
CWE Classification CWE-940: Improper Verification of Source of a Communication Channel
Affected Product MLflow
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 9.6

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-2611

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

mlflow fixed: 3.10.0 
pip install mlflow>=3.10.0
Verify Direct and Transitive Dependencies

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

pip show mlflow

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-2611, inspect your installed packages using pip:

pip show mlflow

Analyze the terminal output to locate any version of MLflow in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.10.0), your application is affected.

Note: The pip show mlflow command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-940: Improper Verification of Source of a Communication Channel, where the product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin. In MLflow, 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

In MLflow version 3.9.0, the MLflow Assistant feature introduced improper origin validation in its /ajax-api endpoints. This vulnerability allows a remote attacker to exploit cross-origin requests from a malicious webpage to interact with the MLflow Assistant running on a victim's local machine. By bypassing the loopback-only restriction, the attacker can modify the Assistant's configuration to enable full access, which in turn allows the execution of arbitrary commands via the Claude Code sub-agent. This issue is resolved in version 3.10.0.

CVE-2026-2611 Affected MLflow Versions

1 component(s)
Fixed Versions:
3.10.0
Product / Package Ecosystem Affected Versions Fixed Version
mlflow
pypi/mlflow
PyPI
≥ 3.9.0
< 3.10.0
All 1 versions
3.9.0
3.10.0

References

NVD — CVE-2026-2611 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-2611
Security Fix Commit FIX COMMIT
https://github.com/mlflow/mlflow/commit/8f9c8a53af90842944101eb8b7d60706822c81bc
MLflow Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-2611
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2479797
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-67c5-x5mf-rppq
MLflow Source Repository REPOSITORY
https://github.com/mlflow/mlflow
MLflow Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/mlflow/PYSEC-2026-418.yaml
huntr.com/bounties/8462addd-b... WEB
https://huntr.com/bounties/8462addd-b464-4a84-b6a2-5529604e6e5a
pypi.org/project/mlflow WEB
https://pypi.org/project/mlflow

Frequently Asked Questions

What is CVE-2026-2611?
CVE-2026-2611 is a security vulnerability in MLflow involving Improper Origin Validation in MLflow Assistant /ajax-api Endpoints Enables Browser-Mediated Local Command Execution under CWE-940: Improper Verification of Source of a Communication Channel.
Which MLflow versions are affected?
Affected versions include releases prior to 3.10.0 across affected packages: mlflow.
What version fixes CVE-2026-2611?
Upgrading to 3.10.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is mlflow affected?
Yes, mlflow is affected in releases prior to 3.10.0. Upgrade your dependency to 3.10.0 or later.
What is the CVSS score of CVE-2026-2611?
CVE-2026-2611 has a CVSS v3.1 base score of 9.6 (CRITICAL) with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.
What CWE is associated with CVE-2026-2611?
CVE-2026-2611 is classified under CWE-940: Improper Verification of Source of a Communication Channel (The product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin.).
How can I check PyPI dependencies for CVE-2026-2611?
Run the dependency tree command: 'pip show mlflow'. 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-67c5-x5mf-rppq",
  "modified" : "2026-10-05T21:33:09Z",
  "published" : "2026-05-19T12:31:37Z",
  "aliases" : [ "CVE-2026-2611" ],
  "summary" : "MLflow: Improper Origin Validation in MLflow Assistant /ajax-api Endpoints Enables Browser-Mediated Local Command Execution",
  "details" : "In MLflow version 3.9.0, the MLflow Assistant feature introduced improper origin validation in its /ajax-api endpoints. This vulnerability allows a remote attacker to exploit cross-origin requests from a malicious webpage to interact with the MLflow Assistant running on a victim's local machine. By bypassing the loopback-only restriction, the attacker can modify the Assistant's configuration to enable full access, which in turn allows the execution of arbitrary commands via the Claude Code sub-agent. This issue is resolved in version 3.10.0.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "mlflow"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.9.0"
      }, {
        "fixed" : "3.10.0"
      } ]
    } ],
    "versions" : [ "3.9.0" ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-2611"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mlflow/mlflow/commit/8f9c8a53af90842944101eb8b7d60706822c81bc"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2026-2611"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2479797"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-67c5-x5mf-rppq"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mlflow/mlflow"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/mlflow/PYSEC-2026-418.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://huntr.com/bounties/8462addd-b464-4a84-b6a2-5529604e6e5a"
  }, {
    "type" : "WEB",
    "url" : "https://pypi.org/project/mlflow"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-346", "CWE-940" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-04T15:23:35Z",
    "nvd_published_at" : "2026-05-19T10:16:22Z"
  }
}