Known exploited vulnerability
CVE-2021-35211
The short answer
CVE-2021-35211 affects SolarWinds Serv-U Managed File Transfer Server and Serv-U Secured FTP and is rated critical (CVSS 10.0). CISA added it to the Known Exploited Vulnerabilities catalog on 2021-11-03: attackers are using it, so patch it first. The vendor has linked a patch.
What it is
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.
Weakness: CWE-787.
Severity
10.0 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Exploited (CISA KEV)
Yes, since Nov 3, 2021
Federal due date Nov 17, 2021
EPSS, next 30 days
91%
Higher than 100% of scored CVEs
How it can be exploited
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
What CISA says to do
Apply updates per vendor instructions.
Affected products
Serv-U Managed File Transfer Server and Serv-U Secured FTP. NVD's record lists the exact affected versions.
References
- www.microsoft.com/security/blog/2021/07/13/microsoft-discovers-threat-actor-targeting-solarwinds-serv-u-software-with-0-day-exploit PatchVendor Advisory
- www.solarwinds.com/trust-center/security-advisories/cve-2021-35211 PatchVendor Advisory
- www.microsoft.com/security/blog/2021/07/13/microsoft-discovers-threat-actor-targeting-solarwinds-serv-u-software-with-0-day-exploit PatchVendor Advisory
- www.solarwinds.com/trust-center/security-advisories/cve-2021-35211 PatchVendor Advisory
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35211 US Government Resource
Questions
Is CVE-2021-35211 being exploited?
Yes. CISA added CVE-2021-35211 to its Known Exploited Vulnerabilities catalog on 2021-11-03, with a federal remediation due date of 2021-11-17. CISA lists it as used in ransomware campaigns.
How do I fix CVE-2021-35211?
CISA's required action: Apply updates per vendor instructions.
From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.
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