CVE-2025-34027 (GCVE-0-2025-34027)
Vulnerability from cvelistv5 – Published: 2025-05-21 21:58 – Updated: 2026-02-26 18:27Title
Versa Concerto Authentication Bypass File Write Remote Code Execution
Summary
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.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-05-28 03:56 UTC
CWE
- CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://projectdiscovery.io/blog/versa-concerto-a… | exploitmitigation |
Impacted products
Previdian
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: 0e7f853b-d718-403b-90c6-788cd6a0127f
Exploited: Yes
Timestamps
First Seen: 2025-08-01
Asserted: 2025-08-01
Scope
Notes: Versa Concerto Authentication Bypass File Write Remote Code Execution | Affected: Versa / Concerto | CVSS: 10.0 (CRITICAL) | EPSS: 0.4522 | Used in malware: unknown | Not yet in CISA KEV: True
Evidence
Type: Public Report
Signal: Successful Exploitation
Confidence: 70%
Source: previdian
Details
| Feed | Previdian (previdian.com) |
|---|---|
| Title | Versa Concerto Authentication Bypass File Write Remote Code Execution |
| Cve Id | CVE-2025-34027 |
| Vendor | Versa |
| Ghsa Id | GHSA-96GF-3RQF-C8M9 |
| Product | Concerto |
| Added Date | 2025-08-01T00:00:00.000Z |
| Cvss Score | 10.0 |
| Epss Score | 0.4522 |
| Previous Ids | |
| Cvss Severity | CRITICAL |
| Virtual Patch | False |
| Cvss Estimated | False |
| Epss Percentile | 0.98749 |
| Used In Malware | unknown |
| Vulnerability Id | CVE-2025-34027 |
| Ahead Of Cisa Kev | None |
| Not Yet In Cisa Kev | True |
References
Created: 2026-10-02 09:09 CEST
| Updated: 2026-10-02 09:09 CEST
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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