// For flags

CVE-2025-34027

Versa Concerto Authentication Bypass File Write Remote Code Execution

Severity Score

10.0
*CVSS v4

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

1
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Attend
*SSVC
Descriptions

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.

*Credits: ProjectDiscovery, Harsh Jaiswal, Rahul Maini, Parth Malhotra
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
System
Vulnerable | Subsequent
Confidentiality
High
High
Integrity
High
High
Availability
Low
Low
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Attack Vector
Network
Attack Complexity
Low
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
Partial
* Common Vulnerability Scoring System
SSVC
  • Decision:Attend
Exploitation
None
Automatable
Yes
Tech. Impact
Total
* Organization's Worst-case Scenario
Timeline
  • 2025-04-15 CVE Reserved
  • 2025-05-21 CVE Published
  • 2025-05-27 EPSS Updated
  • 2025-05-28 CVE Updated
  • 2025-05-28 First Exploit
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
CWE
  • CWE-287: Improper Authentication
  • CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CAPEC
  • CAPEC-29: Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions
  • CAPEC-38: Leveraging/Manipulating Configuration File Search Paths
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Versa
Search vendor "Versa"
 Concerto
Search vendor "Versa" for product "Concerto"
 >= 12.1.2 <= 12.2.0
Search vendor "Versa" for product "Concerto" and version " >= 12.1.2 <= 12.2.0"
en
Affected