Vulnerability in Versa Concerto
CVE-2025-34027
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.
Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.0 (Critical). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.452 (98.7th percentile), scored .
Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 99th percentile — 98.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.452 · newest: 0.452 · change: 0.000
Affected products
- Versa Concerto — versions 12.1.2
- Versa-Networks Concerto — versions 12.1.2, 12.2.1
Weakness classification (CWE)
Public proof-of-concept exploits
References
- projectdiscovery.io/blog/versa-concerto-authentication-bypass-rce (Exploit, Third Party Advisory, exploit, mitigation)
Frequently asked questions
- What is CVE-2025-34027?
- CVE-2025-34027 is a critical-severity vulnerability in Versa Concerto, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 9.0/10. Published 2025-05-21.
- How severe is CVE-2025-34027?
- Critical severity. CVSS v3 base score is 9.0 out of 10.
- Is CVE-2025-34027 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.