CVE-2021-35211 kev+ ransomware in the critical feed json
Serv-U Remote Memory Escape Vulnerability
published 2021-07-14 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-21854
- cvss
- 9.0
- version 3.1, CNA
- cisa kev
- Exploited
- added 2021-11-03, used in ransomware
- epss
- 91.2%
- EPSS 91.2% chance of exploitation in 30 days, percentile 99.8%
- public exploits
- 0
- none known, plus a Nuclei check
Summary
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.
Patch / fix
cisa required action Apply updates per vendor instructions.
- SolarWinds Serv-U Managed File Transfer Server and Serv-U Secured FTP 15.2.3 HF1
Timeline
- Published
- Added to CISA KEV
- CISA patch deadline
- CISA SSVC: exploitation active
Known exploited
- Added
- 5 y ago
- Patch by
- 2021-11-17 (4 y ago)
- Ransomware
- Known to be used in ransomware campaigns
- Required action
- Apply updates per vendor instructions.
- Vendor, product
- SolarWinds, Serv-U
- CISA name
- SolarWinds Serv-U Remote Code Execution Vulnerability
Ransomware
Groups reported to have exploited it in intrusions.
- Clop ransomware gang
reported by research.nccgroup.com
Ransomware Vulnerability Matrix by BushidoUK (github.com/BushidoUK/Ransomware-Vulnerability-Matrix), reformatted per CVE. CC BY 4.0
CISA SSVC
- Exploitation
- Active, exploited in the wild
- Automatable
- no
- Technical impact
- total
- Assessed
- 21 mo ago
Exploit prediction
91.16% chance of exploitation in the next 30 days, higher than 99.8% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- Nuclei template SolarWinds Serv-U FTP - Remote Code Execution nuclei detection template
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 9.0 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H |
| NVD | 3.1 | 10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
| NVD | 2.0 | 10.0 | AV:N/AC:L/Au:N/C:C/I:C/A:C |
Affected products
- SolarWinds Serv-U Managed File Transfer Server and Serv-U Secured FTP
Classification
- Weakness
-
- CWE-787 Out-of-bounds Write
References
-
solarwinds.com
/trust-center/security-advisories/cve-2021-35211
patch, vendor-advisory
-
microsoft.com
/security/blog/2021/07/13/microsoft-discovers-threat-actor-targeting-solarwinds-serv-u-software-with-0-day-exp
patch, vendor-advisory
-
cisa.gov
/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35211
government-resource, us-government-resource
Sources
- CVE List CVE-2021-35211
- NVD CVE-2021-35211
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.