# CVE-2026-43002: OpenStack Horizon has Incorrect Behavior Order

> Unauthenticated attackers can exhaust session storage in OpenStack Horizon by triggering write operations before authentication, causing denial of service.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 May 2026
- **Updated:** 6 May 2026
- **Also known as:** DEBIAN-CVE-2026-43002, GHSA-vxvf-xvm3-p8j5, PYSEC-2026-2520, UBUNTU-CVE-2026-43002

## What is CVE-2026-43002?

CVE-2026-43002 is a medium-severity denial of service vulnerability in OpenStack Horizon, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-696 (Incorrect Behavior Order)

## Which versions are affected by CVE-2026-43002?

3 open source packages ship an affected version, including horizon. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `horizon` | PyPI | From 25.6 | 25.7.3 |
| `horizon` | PyPI | From 25.6 | 25.7.3 |
| `horizon` | PyPI | From 25.6 | 25.7.3 |

Products: Openstack Horizon.

## How do I fix CVE-2026-43002?

Upgrade horizon to 25.7.3 or later.

## Is CVE-2026-43002 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43002 exists.

## Other vulnerabilities in OpenStack Horizon

- [CVE-2012-2144](https://insights.sbomify.com/CVE-2012-2144/): OpenStack Horizon Session Fixation (medium 6.8)
- [CVE-2022-45582](https://insights.sbomify.com/CVE-2022-45582/): Horizon Web Dashboard Open Redirect vulnerability (medium 6.1)
- [CVE-2026-55748](https://insights.sbomify.com/CVE-2026-55748/): OpenStack Horizon RC file generation does not escape special characters in project names (medium 6.0)
- [CVE-2012-3540](https://insights.sbomify.com/CVE-2012-3540/): Open redirect in n/a (medium 5.8)
- [CVE-2013-4471](https://insights.sbomify.com/CVE-2013-4471/): Auth bypass in n/a (medium 5.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43002 and fix it if it is affected.

What it is: CVE-2026-43002 is a medium-severity denial of service vulnerability in OpenStack Horizon, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43002 exists.

Affected packages and fixed versions:
- horizon (PyPI): affected from 25.6; fixed in 25.7.3
- horizon (PyPI): affected from 25.6; fixed in 25.7.3
- horizon (PyPI): affected from 25.6; fixed in 25.7.3

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-43002/ (Markdown: https://insights.sbomify.com/CVE-2026-43002/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43002
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43002
- OSV: https://osv.dev/vulnerability/CVE-2026-43002

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43002/
Summaries are generated and may contain mistakes; the official description above is the record.