CVE-2026-2635: Mlflow Authentication Bypass Vulnerability

CRITICAL
Advisory Identifier: GHSA-gq3w-7jj3-x7gr
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CVSS 9.8
CWE-1393
Published
Advisory Summary

CVE-2026-2635 is a CRITICAL (CVSS 9.8) authentication bypass vulnerability (CWE-1393: Use of Default Password) affecting Mlflow libraries in the PyPI ecosystem. The issue involves mlflow use of default password authentication bypass vulnerability. Remediation is available by upgrading affected packages to version 3.8.0rc0.

CVE-2026-2635 at a Glance

CVE Identifier CVE-2026-2635
GHSA Identifier GHSA-gq3w-7jj3-x7gr
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-1393: Use of Default Password
Affected Product Mlflow
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 9.8

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:N/S:U/C:H/I:H/A:H).

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

How to Fix CVE-2026-2635

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: 3.8.0rc0 
pip install mlflow>=3.8.0rc0
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-2026-2635, 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 3.8.0rc0), 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-1393: Use of Default Password, where the product uses default passwords for potentially critical functionality. 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

This vulnerability allows remote attackers to bypass authentication on affected installations of MLflow. Authentication is not required to exploit this vulnerability. The specific flaw exists within the basic_auth.ini file. The file contains hard-coded default credentials. An attacker can leverage this vulnerability to bypass authentication and execute arbitrary code in the context of the administrator.

CVE-2026-2635 Affected Mlflow Versions

1 component(s)
Fixed Versions:
3.8.0rc0
Product / Package Ecosystem Affected Versions Fixed Version
mlflow
pypi/mlflow
PyPI
< 3.8.0rc0
3.8.0rc0

References

NVD — CVE-2026-2635 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-2635
Mlflow Source Repository REPOSITORY
https://github.com/mlflow/mlflow/pull/19260
Security Fix Commit FIX COMMIT
https://github.com/mlflow/mlflow/commit/5bf2ec2bd4222a18d78631183ac7f6b752afe8a4
Mlflow Source Repository REPOSITORY
https://github.com/mlflow/mlflow
Mlflow Release RELEASE
https://github.com/mlflow/mlflow/releases/tag/v3.8.0rc0
www.zerodayinitiative.com/advisories/zdi-26-1... WEB
https://www.zerodayinitiative.com/advisories/ZDI-26-111

Frequently Asked Questions

What is CVE-2026-2635?
CVE-2026-2635 is a security vulnerability in Mlflow involving MLflow Use of Default Password Authentication Bypass Vulnerability under CWE-1393: Use of Default Password.
Which Mlflow versions are affected?
Affected versions include releases prior to 3.8.0rc0 across affected packages: mlflow.
What version fixes CVE-2026-2635?
Upgrading to 3.8.0rc0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is mlflow affected?
Yes, mlflow is affected in releases prior to 3.8.0rc0. Upgrade your dependency to 3.8.0rc0 or later.
What is the CVSS score of CVE-2026-2635?
CVE-2026-2635 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-2635?
CVE-2026-2635 is classified under CWE-1393: Use of Default Password (The product uses default passwords for potentially critical functionality.).
How can I check PyPI dependencies for CVE-2026-2635?
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-gq3w-7jj3-x7gr",
  "modified" : "2026-03-17T20:02:55Z",
  "published" : "2026-02-21T00:31:43Z",
  "aliases" : [ "CVE-2026-2635" ],
  "summary" : "MLflow Use of Default Password Authentication Bypass Vulnerability",
  "details" : "This vulnerability allows remote attackers to bypass authentication on affected installations of MLflow. Authentication is not required to exploit this vulnerability.\n\nThe specific flaw exists within the basic_auth.ini file. The file contains hard-coded default credentials. An attacker can leverage this vulnerability to bypass authentication and execute arbitrary code in the context of the administrator.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "mlflow"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.8.0rc0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-2635"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mlflow/mlflow/pull/19260"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mlflow/mlflow/commit/5bf2ec2bd4222a18d78631183ac7f6b752afe8a4"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mlflow/mlflow"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mlflow/mlflow/releases/tag/v3.8.0rc0"
  }, {
    "type" : "WEB",
    "url" : "https://www.zerodayinitiative.com/advisories/ZDI-26-111"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1393" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-17T20:02:55Z",
    "nvd_published_at" : "2026-02-20T23:16:05Z"
  }
}