CVE-2025-34027
High PUBLISHEDVersa Concerto Authentication Bypass File Write Remote Code Execution
Not yet in CISA KEV
Recommended Action
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
At a Glance
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.
- CVE Published
- May 21, 2025
- Exploitation Reported
- Aug 01, 2025
- CVSS
- 10.0 Critical
- EPSS
- —
Affected Versions
| Vendor | Product | Version | Status |
|---|---|---|---|
| Versa |
Concerto
|
12.1.2 to <= 12.2.0 |
Affected |
CVE References
- Exploit — projectdiscovery.io projectdiscovery.io · Exploit https://projectdiscovery.io/blog/versa-concerto-authentication-bypass...
Recommended Actions
- Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
- Check enrichment artifacts for scanner coverage and available PoCs before rolling remediation validation.
- Use the Pro API to automate enrichment, telemetry, and workflow delivery for VM, SOC, and CTI pipelines.
Known Exploited Vulnerability Sources
Catalogues that list this CVE as a known exploited vulnerability.
Per-source evidence links for KEV attestations are available through the KEVIntel Pro API.
Learn about Pro API access| Source | Added |
|---|---|
| The Shadowserver First | 2025-08-01 00:00 UTC |
Scanner Artifacts
Nuclei and Metasploit references linked to this CVE.
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2025/CVE-2025-34027.yaml | Jun 01, 2026 |
Virtual Patch
Compensating WAF rules to help reduce exposure to this CVE. Rule content and deployable vendor exports are available with KEVIntel Enterprise.
KEVIntel does not currently have a virtual patch for this CVE. When available, KEVIntel virtual patches ship as deployable ModSecurity, Cloudflare, and AWS WAF rules.
Enterprise feature. Virtual patch rule content and deployable vendor exports (ModSecurity, Cloudflare, AWS WAF) are available to KEVIntel Enterprise users.
CVSS Scores
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
Exploitation Status
Exploited in the wild
Recorded 2025-08-01 00:00:00 UTC · The Shadowserver
Proof of concept available
Recorded 2026-06-12 14:21:06 UTC · Nuclei Templates
Weaknesses (CWE)
-
Time-of-check Time-of-use (TOCTOU) Race Condition
Scanner Integrations
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2025/CVE-2025-34027.yaml | Jun 01, 2026 |
Potential Proof of Concepts
These PoCs are unverified and could contain malware. Use at your own risk.
nuclei · Created Unknown
Timeline
Key exploitation, disclosure, scanner coverage, and KEV attestation events for this CVE.
-
14:21 UTC about 1 month ago14:21 UTC · about 1 month ago
Public PoC available
Public proof-of-concept code published
-
15:34 UTC about 2 months ago15:34 UTC · about 2 months ago
Nuclei template available
Scanner coverage available
-
00:00 UTC 12 months ago00:00 UTC · 12 months ago
Added to KEVIntel KEV Feed
High-confidence, third-party attested exploitation
-
21:58 UTC about 1 year ago21:58 UTC · about 1 year ago
CVE published
Vulnerability disclosed publicly
-
19:15 UTC over 1 year ago19:15 UTC · over 1 year ago
CVE ID reserved
Identifier reserved by the CNA
Automate This Intelligence with the Pro API
Confidence scoring, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
Pro API Example
GET /api/v2/pro/kevs/CVE-2025-34027
{
"cve_id": "CVE-2025-34027",
"title": "Versa Concerto Authentication Bypass File Write Remote Code Execution",
"affected_vendor": "Versa",
"affected_product": "Concerto",
"affected_versions": [
{ "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
],
"confidence": "High",
"cvss_score": 10.0,
"epss_score": null,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "...": "Pro API fields" },
"proof_of_concepts": [ "..." ],
"scanner_integrations": [ "..." ]
}