---
cve: "CVE-2025-34027"
severity: "CRITICAL"
cvss: 10.0
epss: "46.4%"
vendor: "Versa"
kev: false
exploited: false
published: "2025-05-21 21:58:31"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-11-09T15:04:15+01:00"
---

# CVE-2025-34027

> 10.0 CRITICAL

## Beschreibung

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.

## CNA-Record (Kanon, cvelistV5)

- CNA: **VulnCheck**
- State: PUBLISHED
- Stand: 2026-02-26 18:27:59
- CNA-CVSS: **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`)

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **none**
  - Automatable: **yes**
  - Technical Impact: **total**

## CVSS-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Schwachstellen-Klasse

- **CWE-367** — Time-of-check Time-of-use (TOCTOU) Race Condition
  The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

## Angriffsmuster (CAPEC)

- [CAPEC-27 — Leveraging Race Conditions via Symbolic Links](https://capec.mitre.org/data/definitions/27.html) _(Severity: High)_
- [CAPEC-29 — Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions](https://capec.mitre.org/data/definitions/29.html) _(Severity: High)_

## Referenzen

- <https://projectdiscovery.io/blog/versa-concerto-authentication-bypass-rce>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/sicherheitsluecken/cve-2025-34027/) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_