{"id":"CVE-2021-20123","kind":"vulnerability","aliases":["CVE-2021-20123"],"related":[],"title":"A local file inclusion vulnerability exists in Draytek VigorConnect 1.6.0-B3 in the file download functionality of…","description":"Draytek VigorConnect contains a path traversal vulnerability in the DownloadFileServlet endpoint. An unauthenticated attacker could leverage this vulnerability to download arbitrary files from the underlying operating system with root privileges.\n\nCISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.","summary":"DrayTek VigorConnect, a management server for DrayTek network devices, has a path traversal flaw in its DownloadFileServlet endpoint. An unauthenticated attacker can download arbitrary files from the server's operating system with root privileges.","severity":"critical","cvss":7.8,"epss":null,"exploited":true,"exploited_at":"2024-09-03T00:00:00+00:00","products":[{"name":"DrayTek VigorConnect","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"draytek vigorconnect","fixed":[],"affected":"= 1.6.0","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["draytek","exploited","infrastructure","self-hosted","vigorconnect"],"not_affected_if":["not-running-vigorconnect"],"how_to_check":null,"fix":"Apply the vendor mitigations per DrayTek instructions, or stop using VigorConnect if no mitigation is available (per CISA KEV required action).","status":"open","published_at":"2021-10-13T16:15:07+00:00","first_seen_at":"2026-10-23T19:11:51+00:00","triaged_at":"2026-10-23T20:58:15+00:00","updated_at":"2026-10-23T22:29:05+00:00","category":"infrastructure","confidence":0.7,"triage":{"at":"2026-10-23T20:58:15Z","model":"claude-haiku-5-5","output":{"fix":"Apply the vendor mitigations per DrayTek instructions, or stop using VigorConnect if no mitigation is available (per CISA KEV required action).\nunknown","reach":"internet","impact":"high","summary":"DrayTek VigorConnect, a management server for DrayTek network devices, has a path traversal flaw in its DownloadFileServlet endpoint. An unauthenticated attacker can download arbitrary files from the server's operating system with root privileges.","category":"infrastructure","who_cares":["draytek","vigorconnect","self-hosted"],"confidence":0.7,"needs_auth":"no","worst_case":"Unauthenticated attacker reads any server file as root, including secrets.","analyst_note":"Affected and fixed versions and the exact mitigation are not in the sources; check DrayTek's advisory and the CISA KEV entry for CVE-2021-20123.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["not-running-vigorconnect"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"critical"},"cost_usd":0.000477,"input_tokens":2845,"output_tokens":385,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-20123':19A,22A '-2021':18A,21A '1.6.0':10A 'action':100C 'appli':101C 'arbitrari':57B,88C 'attack':54B,81C 'b3':11A 'cisa':98C 'contain':70C 'could':82C 'cve':17A,20A 'devic':42B 'discontinu':107C 'download':15A,56B,87C 'downloadfileservlet':50B,77C 'draytek':8A,23A,25A,27B,34B,40B,68C 'endpoint':51B,78C 'exist':6A 'exploit':28B 'file':3A,14A,58B,89C 'flaw':47B 'function':16A 'host':32B 'inclus':4A 'infrastructur':29B 'instruct':105C 'leverag':83C 'local':2A 'manag':37B 'mitig':102C,113C 'network':41B 'oper':63B,93C 'path':45B,72C 'per':103C 'privileg':67B,97C 'product':111C 'requir':99C 'root':66B,96C 'self':31B 'self-host':30B 'server':38B,61B 'system':64B,94C 'travers':46B,73C 'unauthent':53B,80C 'unavail':115C 'under':92C 'use':108C 'vendor':104C 'vigorconnect':9A,24A,26A,33B,35B,69C 'vulner':5A,74C,85C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-10-13T16:15:07+00:00","kev":{"dateAdded":"2024-09-03","dueDate":"2024-09-24","requiredAction":"Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","cvss_by":"nvd@nist.gov","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-20123","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-20123","severity":null,"published_at":"2024-09-03T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:51+00:00","fetched_at":"2026-10-25T17:39:56+00:00","note":null},{"source":"nvd","external_id":"CVE-2021-20123","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-20123","severity":null,"published_at":"2021-10-13T16:15:07+00:00","modified_at":"2026-06-17T03:33:18+00:00","first_seen_at":"2026-10-23T22:29:05+00:00","fetched_at":"2026-10-23T22:29:05+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"}