What it is
CVE-2021-35211 is an unauthenticated Serv-U Remote Memory Escape Vulnerability affecting SolarWinds Serv-U Managed File Transfer Server and Serv-U Secured FTP. Microsoft discovered a remote code execution (RCE)...
Vulnerability report
Exploited in the wild
Confirmed confidence
In CISA KEV
CVE-2021-35211
Serv-U Remote Memory Escape Vulnerability
SolarWinds / Serv-U Managed File Transfer Server and Serv-U Secured FTP · affected before 15.2.3 HF1
- Severity
- CVSS 9.0 · Critical
- Confidence
- Confirmed
- Exploit status
- Exploited in the wild
- EPSS
- 91.2%
- First observed
- —
- Last observed
- —
Decision summary
What security teams need to know first
Direct answers before the deeper technical record.
Is it exploited?
Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.
Who is affected?
SolarWinds / Serv-U Managed File Transfer Server and Serv-U Secured FTP affected before 15.2.3 hf1.
What should we do?
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
Overview
Serv-U Remote Memory Escape Vulnerability
Microsoft discovered a remote code execution (RCE) vulnerability in the SolarWinds Serv-U product utilizing a Remote Memory Escape Vulnerability. If exploited, a threat actor may be able to gain privileged access to the machine hosting Serv-U Only.
SolarWinds Serv-U Managed File Transfer and Serv-U Secure FTP for Windows before 15.2.3 HF2 are affected by this vulnerability.
Vendor
Product
Affected
Status
SolarWinds
Serv-U Managed File Transfer Server and Serv-U Secured FTP
Before 15.2.3 HF1
Affected
- Published
- 14 Jul 2021
- Exploitation Reported
- 03 Nov 2021
- Attack vector
- Remote
- Complexity
- High
- Privileges
- None
- User interaction
- None
Tags
nuclei_scanner
malware
windows
ransomware
cisa
CVE References
- CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2021-35211
- solarwinds.com/trust-center/security-advisories/cve-2021-35211 solarwinds.com · CVE Record https://www.solarwinds.com/trust-center/security-advisories/cve-2021-...
- microsoft.com/security/blog/2021/07/13/microsoft-discovers... microsoft.com · CVE Record https://www.microsoft.com/security/blog/2021/07/13/microsoft-discover...
Exploitation evidence
Why KEV Intelligence marks this CVE as exploited
Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.
Exploited in the wild
CISA
Independent exploitation attestation added to the KEV Intelligence record.
Used in malware
CISA
Malware families have been linked to exploitation of this CVE.
Proof of concept available
GitHub
Public scanner or PoC coverage increases practical exploitability.
Known exploited vulnerability sources
Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.
Learn about Pro API access| Source | Added |
|---|---|
| CISA First | 2021-11-03 00:00 UTC |
Detection
Operational artifacts and observed signals
Make the evidence actionable in scanner, SOC, and edge-control workflows.
Observed signals
- Request targets
- 0
- User-Agents
- 0
Raw values available in Pro and Enterprise.
Scanner coverage
Nuclei template detected 01 Jun 2026.
View Nuclei template (opens in new tab)Virtual patch status
No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.
Learn about virtual patches →Scanner Artifacts
Scanner and exploit-framework references linked to this CVE.
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/javascript/cves/2021/CVE-2021-35211.yaml | 01 Jun 2026 |
Risk and context
Severity, weaknesses, and research context
CVSS v3.1
9.0
Critical
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS
91.2%
Weaknesses
Potential Proof of Concepts
These PoCs are unverified and could contain malware. Use at your own risk.
BishopFox/CVE-2021-35211
github · Created 2022-01-14 05:52:17 UTC · 35 stars · AI assessment 90%
SolarWinds Serv-U FTP - Remote Code Execution
nuclei · Created Unknown
Timeline
From disclosure to observed exploitation
-
Nuclei template available
Scanner coverage available
-
Public PoC available
Public proof-of-concept code published
-
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
First public exploitation report
Exploit observed in malware
-
CVE published
Vulnerability disclosed publicly
-
CVE ID reserved
Identifier reserved by the CNA
Pro API
Automate this intelligence
Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
- Evidence confidence and provenance
- First-party sensor telemetry
- PoC and scanner references
- Affected versions and enrichment
- Automation-ready JSON delivery
GET /api/v2/pro/kevs/CVE-2021-35211
Free JSON includes basic KEV fields{
"cve_id": "CVE-2021-35211",
"confidence": "Confirmed",
"cvss_score": 9.0,
"cvss_estimated": false,
"epss_score": 0.9116,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "attempts": 0, "sensors": 0 }
}Early warning alerts
Get alerts on high-impact exploitation
Receive curator-selected alerts when exploitation activity warrants attention. Each alert includes the evidence and context needed to decide what requires attention now.