CVE-2026-43002: Horizon OpenStack Horizon Has Incorrect Behavior Vulnerability

MODERATE
Advisory Identifier: GHSA-vxvf-xvm3-p8j5
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CVSS 5.3
CWE-696
Published
Advisory Summary

CVE-2026-43002 is a MODERATE (CVSS 5.3) openstack horizon has incorrect behavior vulnerability (CWE-696: Incorrect Behavior Order) affecting Horizon libraries in the PyPI ecosystem. The issue involves openstack horizon has incorrect behavior order. Remediation is available by upgrading affected packages to version 25.7.3.

CVE-2026-43002 at a Glance

CVE Identifier CVE-2026-43002
GHSA Identifier GHSA-vxvf-xvm3-p8j5
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-696: Incorrect Behavior Order
Affected Product Horizon
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.3

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

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 None (C:N)
Integrity None (I:N)
Availability Low (A:L)

How to Fix CVE-2026-43002

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

horizon fixed: 25.7.3 
pip install horizon>=25.7.3
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 horizon

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-43002, inspect your installed packages using pip:

pip show horizon

Analyze the terminal output to locate any version of Horizon in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 25.7.3), your application is affected.

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

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-696: Incorrect Behavior Order, where the product performs multiple related behaviors, but the behaviors are performed in the wrong order in ways that may produce resultant weaknesses. In Horizon, 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

An issue was discovered in OpenStack Horizon 25.6 and 25.7 before 25.7.3. There is a write operation to the session storage backend before authentication and thus storage can be exhausted by unauthenticated requests. This is a regression of the CVE-2014-8124 fix.

CVE-2026-43002 Affected Horizon Versions

1 component(s)
Fixed Versions:
25.7.3
Product / Package Ecosystem Affected Versions Fixed Version
horizon
pypi/horizon
PyPI
≥ 25.6
< 25.7.3
25.7.3

References

NVD — CVE-2026-43002 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-43002
bugs.launchpad.net/horizon/+bug/215033... WEB
https://bugs.launchpad.net/horizon/+bug/2150331
Horizon Source Repository REPOSITORY
https://github.com/openstack/horizon
Horizon Security Information SECURITY
https://security.openstack.org/ossa/OSSA-2026-009.html
Horizon Security Information SECURITY
https://www.openwall.com/lists/oss-security/2026/05/05/7

Frequently Asked Questions

What is CVE-2026-43002?
CVE-2026-43002 is a security vulnerability in Horizon involving OpenStack Horizon has Incorrect Behavior Order under CWE-696: Incorrect Behavior Order.
Which Horizon versions are affected?
Affected versions include releases prior to 25.7.3 across affected packages: horizon.
What version fixes CVE-2026-43002?
Upgrading to 25.7.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is horizon affected?
Yes, horizon is affected in releases prior to 25.7.3. Upgrade your dependency to 25.7.3 or later.
What is the CVSS score of CVE-2026-43002?
CVE-2026-43002 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
What CWE is associated with CVE-2026-43002?
CVE-2026-43002 is classified under CWE-696: Incorrect Behavior Order (The product performs multiple related behaviors, but the behaviors are performed in the wrong order in ways that may produce resultant weaknesses.).
How can I check PyPI dependencies for CVE-2026-43002?
Run the dependency tree command: 'pip show horizon'. 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-vxvf-xvm3-p8j5",
  "modified" : "2026-05-08T22:19:51Z",
  "published" : "2026-05-05T18:33:27Z",
  "aliases" : [ "CVE-2026-43002" ],
  "summary" : "OpenStack Horizon has Incorrect Behavior Order",
  "details" : "An issue was discovered in OpenStack Horizon 25.6 and 25.7 before 25.7.3. There is a write operation to the session storage backend before authentication and thus storage can be exhausted by unauthenticated requests. This is a regression of the CVE-2014-8124 fix.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "horizon"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "25.6"
      }, {
        "fixed" : "25.7.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-43002"
  }, {
    "type" : "WEB",
    "url" : "https://bugs.launchpad.net/horizon/+bug/2150331"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/openstack/horizon"
  }, {
    "type" : "WEB",
    "url" : "https://security.openstack.org/ossa/OSSA-2026-009.html"
  }, {
    "type" : "WEB",
    "url" : "https://www.openwall.com/lists/oss-security/2026/05/05/7"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-696" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-08T22:19:51Z",
    "nvd_published_at" : "2026-05-05T17:17:04Z"
  }
}