{"id":"CVE-2021-35211","kind":"vulnerability","aliases":["CVE-2021-35211"],"related":[],"title":"SolarWinds Serv-U: SolarWinds Serv-U Remote Code Execution Vulnerability","description":"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.","summary":"SolarWinds Serv-U, a managed file transfer server, has a memory escape flaw that lets a remote attacker run code on the server. CISA lists it as actively exploited, and the KEV entry notes known ransomware use.","severity":"critical","cvss":10.0,"epss":0.9116,"exploited":true,"exploited_at":"2021-11-03T00:00:00+00:00","products":[{"name":"SolarWinds Serv-U","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["exploited","file-transfer","infrastructure","ransomware","serv-u","solarwinds","windows"],"not_affected_if":["no-serv-u-installed"],"how_to_check":"Identify Serv-U installs and their versions in the admin console or the installed package; the affected and fixed version ranges are unknown from the sources.","fix":"Apply the vendor's updates per SolarWinds instructions (per CISA required action); the specific fixed version is unknown from the sources.","status":"open","published_at":"2021-07-14T21:15:08+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:41:28+00:00","updated_at":"2026-10-23T21:57:34+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-23T21:41:28Z","model":"claude-haiku-5-5","output":{"fix":"Apply the vendor's updates per SolarWinds instructions (per CISA required action); the specific fixed version is unknown from the sources.\nunknown","reach":"internet","impact":"high","summary":"SolarWinds Serv-U, a managed file transfer server, has a memory escape flaw that lets a remote attacker run code on the server. CISA lists it as actively exploited, and the KEV entry notes known ransomware use.","category":"infrastructure","who_cares":["solarwinds","serv-u","file-transfer","windows"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Attacker runs code remotely on the Serv-U server, enabling ransomware deployment.","analyst_note":"Find the affected and fixed Serv-U versions and the exact vulnerable configuration via the SolarWinds security advisory and the CISA KEV entry (https://www.cisa.gov/known-exploited-vulnerabilities-catalog).","how_to_check":"Identify Serv-U installs and their versions in the admin console or the installed package; the affected and fixed version ranges are unknown from the sources.\nunknown\nunknown","needs_analyst":true,"not_affected_if":["no-serv-u-installed"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000514,"input_tokens":2830,"output_tokens":461,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':14A,17A '-35211':15A,18A '15.2.3':129C 'abl':100C 'access':104C 'activ':62B 'actor':97C 'affect':132C 'attack':52B 'cisa':58B 'code':10A,54B,76C 'cve':13A,16A 'discov':73C 'entri':67B 'escap':46B,91C 'execut':11A,77C 'exploit':23B,63B,94C 'file':25B,40B,118C 'file-transf':24B 'flaw':47B 'ftp':125C 'gain':102C 'hf2':130C 'host':108C 'infrastructur':27B 'kev':66B 'known':69B 'let':49B 'list':59B 'machin':107C 'manag':39B,117C 'may':98C 'memori':45B,90C 'microsoft':72C 'note':68B 'privileg':103C 'product':86C 'ransomwar':28B,70B 'rce':78C 'remot':9A,51B,75C,89C 'run':53B 'secur':124C 'serv':3A,7A,21A,30B,36B,84C,110C,115C,122C 'serv-u':2A,6A,20A,29B,35B,83C,109C,114C,121C 'server':42B,57B 'solarwind':1A,5A,32B,34B,82C,113C 'solarwinds':19A 'threat':96C 'transfer':26B,41B,119C 'u':4A,8A,22A,31B,37B,85C,111C,116C,123C 'use':71B 'util':87C 'vulner':12A,79C,92C,135C 'window':33B,127C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-07-14T21:15:08+00:00","kev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Known"},"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H","cvss_by":"psirt@solarwinds.com","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-35211","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-35211","severity":null,"published_at":"2021-11-03T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:53+00:00","fetched_at":"2026-10-25T15:39:44+00:00","note":null},{"source":"epss","external_id":"CVE-2021-35211","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-35211","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:43+00:00","fetched_at":"2026-10-23T19:13:43+00:00","note":null},{"source":"nvd","external_id":"CVE-2021-35211","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-35211","severity":null,"published_at":"2021-07-14T21:15:08+00:00","modified_at":"2026-06-17T03:57:18+00:00","first_seen_at":"2026-10-23T21:57:34+00:00","fetched_at":"2026-10-23T21:57:34+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}