# CVE-2025-34027: Versa Concerto Authentication Bypass File Write Remote Code Execution

> Unauthenticated attackers can bypass authentication and exploit a race condition to achieve remote code execution on Versa Concerto SD-WAN platforms.

- **Severity:** Critical 10.0 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 May 2025
- **Updated:** 26 Feb 2026
- **Also known as:** GHSA-96gf-3rqf-c8m9

## What is CVE-2025-34027?

CVE-2025-34027 is a critical authentication bypass vulnerability in Versa Concerto, published on 21 May 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Versa Concerto SD-WAN orchestration platform is vulnerable to an authentication bypass in the Traefik reverse proxy configuration, allowing at attacker to access administrative endpoints. The Spack upload endpoint can be leveraged for a Time-of-Check to Time-of-Use (TOCTOU) write in combination with a race condition to achieve remote code execution via path loading manipulation, allowing an unauthenticated actor to achieve remote code execution (RCE).This issue is known to affect Concerto from 12.1.2 through 12.2.0. Additional versions may be vulnerable.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2025-34027?

It affects 1 product.


Products: Versa-Networks Concerto.

## How do I fix CVE-2025-34027?

No fix has been published for CVE-2025-34027 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-34027 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-34027 exists.

Public exploit code:

- Versa Concerto API Path Based - Authentication Bypass (nuclei): http/cves/2025/CVE-2025-34027.yaml

## Other vulnerabilities in Versa Concerto

- [CVE-2025-34026](https://insights.sbomify.com/CVE-2025-34026/): Versa Concerto Improper Authentication (critical 9.2, exploited in the wild)
- [CVE-2025-34025](https://insights.sbomify.com/CVE-2025-34025/): Versa Concerto Insecure Docker Mount Container Escape (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-34027 and fix it if it is affected.

What it is: CVE-2025-34027 is a critical authentication bypass vulnerability in Versa Concerto, published on 21 May 2025. 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-2025-34027 exists.

Affected product: Versa Concerto. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2025-34027/ (Markdown: https://insights.sbomify.com/CVE-2025-34027/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-34027
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-34027
- OSV: https://osv.dev/vulnerability/CVE-2025-34027

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-34027/
Summaries are generated and may contain mistakes; the official description above is the record.