CVE-2021-35211
Confirmed PUBLISHEDServ-U Remote Memory Escape Vulnerability
Recommended Action
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
At a Glance
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.
- CVE Published
- Jul 14, 2021
- Exploitation Reported
- Nov 03, 2021
- CVSS
- 9.0 Critical
- EPSS
- —
Affected Versions
| Vendor | Product | Version | Status |
|---|---|---|---|
| SolarWinds |
Serv-U Managed File Transfer Server and Serv-U Secured FTP
|
SolarWinds Serv-U to < 15.2.3 HF1 |
Affected |
CVE References
- 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...
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 |
|---|---|
| CISA First | 2021-11-03 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/javascript/cves/2021/CVE-2021-35211.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:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Exploitation Status
Exploited in the wild
Recorded 2021-11-03 00:00:00 UTC · CISA
Used in malware
Recorded 2021-11-03 00:00:00 UTC · CISA
Proof of concept available
Recorded 2021-09-30 01:45:42 UTC · GitHub
Weaknesses (CWE)
-
Out-of-bounds Write
Scanner Integrations
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/javascript/cves/2021/CVE-2021-35211.yaml | Jun 01, 2026 |
Potential Proof of Concepts
These PoCs are unverified and could contain malware. Use at your own risk.
github · Created 2022-01-14 05:52:17 UTC · 35 stars
github · Created 2021-09-30 01:45:42 UTC · 12 stars
Simple Serv-U CVE-2021-35211 PoC
nuclei · Created Unknown
Timeline
Key exploitation, disclosure, scanner coverage, and KEV attestation events for this CVE.
-
15:34 UTC about 2 months ago15:34 UTC · about 2 months ago
Nuclei template available
Scanner coverage available
-
00:00 UTC over 4 years ago00:00 UTC · over 4 years ago
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
00:00 UTC over 4 years ago00:00 UTC · over 4 years ago
First public exploitation report
Exploit observed in malware
-
01:45 UTC almost 5 years ago01:45 UTC · almost 5 years ago
Public PoC available
Public proof-of-concept code published
-
20:55 UTC about 5 years ago20:55 UTC · about 5 years ago
CVE published
Vulnerability disclosed publicly
-
00:00 UTC about 5 years ago00:00 UTC · about 5 years 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-2021-35211
{
"cve_id": "CVE-2021-35211",
"title": "Serv-U Remote Memory Escape Vulnerability",
"affected_vendor": "SolarWinds",
"affected_product": "Serv-U Managed File Transfer Server and Serv-U Secured FTP",
"affected_versions": [
{ "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
],
"confidence": "Confirmed",
"cvss_score": 9.0,
"epss_score": null,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "...": "Pro API fields" },
"proof_of_concepts": [ "..." ],
"scanner_integrations": [ "..." ]
}