CVE-2026-6859: Instructlab InstructLab Includes Functionality From Untrusted Vulnerability

HIGH
Advisory Identifier: GHSA-rxpq-xgqx-fr7p
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CVSS 8.8
CWE-829
Published
Advisory Summary

CVE-2026-6859 is a HIGH (CVSS 8.8) instructlab includes functionality from untrusted vulnerability (CWE-829: Inclusion of Functionality from Untrusted Control Sphere) affecting Instructlab libraries in the PyPI ecosystem. The issue involves instructlab includes functionality from untrusted control sphere. Remediation is available in the latest vendor maintenance releases.

CVE-2026-6859 at a Glance

CVE Identifier CVE-2026-6859
GHSA Identifier GHSA-rxpq-xgqx-fr7p
Severity HIGH
CVSS v3.1 Base Score 8.8
CWE Classification CWE-829: Inclusion of Functionality from Untrusted Control Sphere
Affected Product Instructlab
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 8.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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 Required (UI:R)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-6859

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

instructlab fixed: Latest secure release 
pip install instructlab>=Latest secure release
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 instructlab

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-6859, inspect your installed packages using pip:

pip show instructlab

Analyze the terminal output to locate any version of Instructlab 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 pip show instructlab command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-829: Inclusion of Functionality from Untrusted Control Sphere, where the product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere. In Instructlab, 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

A flaw was found in InstructLab. The `linux_train.py` script hardcodes `trust_remote_code=True` when loading models from HuggingFace. This allows a remote attacker to achieve arbitrary Python code execution by convincing a user to run `ilab train/download/generate` with a specially crafted malicious model from the HuggingFace Hub. This vulnerability can lead to complete system compromise.

CVE-2026-6859 Affected Instructlab Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
instructlab
pypi/instructlab
PyPI
≤ 0.26.1

References

NVD — CVE-2026-6859 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-6859
Instructlab Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-6859
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2459998
Instructlab Source Repository REPOSITORY
https://github.com/instructlab/instructlab

Frequently Asked Questions

What is CVE-2026-6859?
CVE-2026-6859 is a security vulnerability in Instructlab involving InstructLab Includes Functionality from Untrusted Control Sphere under CWE-829: Inclusion of Functionality from Untrusted Control Sphere.
Which Instructlab versions are affected?
Affected versions include releases prior to current release patches across affected packages: instructlab.
What version fixes CVE-2026-6859?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is instructlab affected?
Yes, instructlab is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2026-6859?
CVE-2026-6859 has a CVSS v3.1 base score of 8.8 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-6859?
CVE-2026-6859 is classified under CWE-829: Inclusion of Functionality from Untrusted Control Sphere (The product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere.).
How can I check PyPI dependencies for CVE-2026-6859?
Run the dependency tree command: 'pip show instructlab'. 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-rxpq-xgqx-fr7p",
  "modified" : "2026-04-29T22:08:37Z",
  "published" : "2026-04-22T15:31:45Z",
  "aliases" : [ "CVE-2026-6859" ],
  "summary" : "InstructLab Includes Functionality from Untrusted Control Sphere",
  "details" : "A flaw was found in InstructLab. The `linux_train.py` script hardcodes `trust_remote_code=True` when loading models from HuggingFace. This allows a remote attacker to achieve arbitrary Python code execution by convincing a user to run `ilab train/download/generate` with a specially crafted malicious model from the HuggingFace Hub. This vulnerability can lead to complete system compromise.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "instructlab"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "0.26.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-6859"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2026-6859"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2459998"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/instructlab/instructlab"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-829" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-29T22:08:37Z",
    "nvd_published_at" : "2026-04-22T14:17:07Z"
  }
}