Exploited vulnerability · CISA KEV

Is CVE-2021-35211 exploited? Yes: in CISA KEV since 3 Nov 2021

Gociux · SolarWinds Serv-U · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2021-35211, SolarWinds Serv-U Remote Code Execution Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 3 Nov 2021, 112 days after it was published. It is known to be used in ransomware campaigns. It affects SolarWinds Serv-U. If you run it, CISA's required action is: Apply updates per vendor instructions.

What it is

SolarWinds Serv-U contains an unspecified memory escape vulnerability which can allow for remote code execution.

What to do

1. Check whether you run it. Look for Serv-U in your asset inventory, including appliances and cloud images. Stack check lists every exploited SolarWinds CVE at once.
2. Apply the fix. Apply updates per vendor instructions.
3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 14 Jul 2021.
4. Get told next time. Email alerts when CISA adds a CVE for SolarWinds.

Other exploited CVEs in Serv-U

• CVE-2026-28318: SolarWinds Serv-U Uncontrolled Resource Consumption Vulnerability (5 Jun 2026)
• CVE-2024-28995: SolarWinds Serv-U Path Traversal Vulnerability (17 Jul 2024)
• CVE-2021-35247: SolarWinds Serv-U Improper Input Validation Vulnerability (21 Jan 2022)

References

• nvd.nist.gov/vuln/detail/CVE-2021-35211

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in November 2021 · SolarWinds scorecard · act-now radar.