CVE-2021-35211

CVE-2021-35211 is a critical-severity (CVSS 9.0) vulnerability in SolarWinds Serv-U. CISA added it to the Known Exploited Vulnerabilities catalog on November 3, 2021, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by November 17, 2021. CISA also lists it as known to be used in ransomware campaigns, so it should be prioritised accordingly. SolarWinds has 11 vulnerabilities in the KEV catalog, 2 of them linked to ransomware.

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.

CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

• https://www.microsoft.com/security/blog/2021/07/13/microsoft-discovers-threat-actor-targeting-solarwinds-serv-u-software-with-0-day-exploit
• https://www.solarwinds.com/trust-center/security-advisories/cve-2021-35211
• https://www.microsoft.com/security/blog/2021/07/13/microsoft-discovers-threat-actor-targeting-solarwinds-serv-u-software-with-0-day-exploit
• https://www.solarwinds.com/trust-center/security-advisories/cve-2021-35211
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35211