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PatchSiren cyber security CVE debrief

CVE-2021-35211 SolarWinds CVE debrief

CVE-2021-35211 is a SolarWinds Serv-U remote code execution vulnerability that CISA added to its Known Exploited Vulnerabilities catalog on 2021-11-03. CISA marked it as known to be used in ransomware campaigns and directed affected organizations to apply updates per vendor instructions. Because it is in KEV, this issue should be treated as an active exposure rather than a routine patch item.

Vendor
SolarWinds
Product
Serv-U
CVSS
CRITICAL 9
CISA KEV
Listed
Original CVE published
2021-11-03
Original CVE updated
2021-11-03
Advisory published
2021-11-03
Advisory updated
2021-11-03

Who should care

Organizations running SolarWinds Serv-U, especially security teams, server administrators, and vulnerability management teams responsible for internet-facing managed file transfer services.

Technical summary

The available official records identify this issue as a remote code execution vulnerability in SolarWinds Serv-U. CISA’s KEV entry indicates known exploitation and notes ransomware campaign use. The recommended remediation in the source data is to apply updates per vendor instructions.

Defensive priority

High. KEV inclusion and known ransomware campaign use make this a priority for rapid patching and validation on any affected Serv-U deployment.

Recommended defensive actions

  • Apply the vendor-recommended updates for SolarWinds Serv-U as soon as possible.
  • Confirm whether any Serv-U instances are deployed, including internet-facing servers.
  • Prioritize remediation and verification on systems exposed externally or handling sensitive file transfers.
  • Review security monitoring and incident response readiness for affected hosts because CISA lists this CVE as known exploited.
  • Track closure against CISA KEV requirements and document patch status for all affected assets.

Evidence notes

This debrief relies on the supplied CISA KEV source item and official links to the CVE record, NVD detail page, and CISA KEV catalog. The source item identifies the vulnerability as a SolarWinds Serv-U remote code execution issue, marks it as known exploited, and states known ransomware campaign use. The source also provides the remediation note: apply updates per vendor instructions. No additional technical exploit details were used.

Sources and references

Verified primary and authoritative sources

  • CVE-2021-35211 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2021-35211

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2021-35211 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2021-35211

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

  • CISA Known Exploited Vulnerabilities catalog

    Publisher, destination, and source semantics verified

    URL: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

    Cybersecurity and Infrastructure Security Agency - Official CISA catalog of vulnerabilities known to be exploited in the wild.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

    cisa_kev

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.