{"cve":{"cve_id":"CVE-2021-29441","is_kev":false,"kev_date_added":null,"kev_vendor_project":null,"kev_product":null,"kev_vulnerability_name":null,"kev_short_description":null,"kev_required_action":null,"kev_due_date":null,"kev_known_ransomware":null,"kev_notes":null,"kev_cwes":null,"epss_score":0.74818,"epss_percentile":0.99438,"epss_as_of":"2026-06-23","description":"Nacos is a platform designed for dynamic service discovery and configuration and service management. In Nacos before version 1.4.1, when configured to use authentication (-Dnacos.core.auth.enabled=true) Nacos uses the AuthFilter servlet filter to enforce authentication. This filter has a backdoor that enables Nacos servers to bypass this filter and therefore skip authentication checks. This mechanism relies on the user-agent HTTP header so it can be easily spoofed. This issue may allow any user to carry out any administrative tasks on the Nacos server.","published_at":"2021-04-27T20:20:20Z","last_modified_at":null,"cvss_v3_score":8.6,"cvss_v3_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","cvss_v3_severity":"HIGH","cvss_v4_score":null,"cvss_v4_vector":null,"cvss_v4_severity":null,"ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-290"],"nvd_references":["https://github.com/alibaba/nacos/issues/4701","https://github.com/advisories/GHSA-36hp-jr8h-556f","https://github.com/alibaba/nacos/pull/4703"],"vuln_status":null,"trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-06-24T00:09:39.878444Z","updated_at":"2026-06-28T23:15:28.185384Z"},"effective_severity":"HIGH","badges":["poc","epss"],"impact_analysis":[],"cvss_v3_decoded":{"version":"3.1","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"L","value_label":"Low"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"S","name":"Scope","value":"C","value_label":"Changed"},{"metric":"C","name":"Confidentiality","value":"H","value_label":"High"},{"metric":"I","name":"Integrity","value":"N","value_label":"None"},{"metric":"A","name":"Availability","value":"N","value_label":"None"}]},"cvss_v4_decoded":{"version":null,"metrics":[]},"affected":[{"vendor_slug":"alibaba","vendor_name":"Alibaba","product_slug":"nacos","product_name":"nacos","version_start":"< 1.4.1","version_start_inclusive":true,"version_end":"< 1.4.1","version_end_inclusive":true,"cpe23_uri":"cve5:alibaba:nacos:< 1.4.1:< 1.4.1"}],"exploit_refs":[{"source":"nuclei","kind":"nuclei","url":"https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-29441.yaml","title":"Nacos <1.4.1 - Authentication Bypass","author":"dwisiswant0","disclosed_at":null}],"news":[],"references":[{"url":"https://github.com/alibaba/nacos/issues/4701","source_type":"MISC","tags":[]},{"url":"https://github.com/advisories/GHSA-36hp-jr8h-556f","source_type":"VENDOR_ADVISORY","tags":["advisory"]},{"url":"https://github.com/alibaba/nacos/pull/4703","source_type":"PATCH","tags":["patch"]}],"timeline":[{"type":"published","at":"2021-04-27T20:20:20Z","label":"CVE published","source":null},{"type":"poc_available","at":"2026-06-24T00:29:48.638073Z","label":"Public PoC available","source":"nuclei"},{"type":"cvss_changed","at":"2026-06-28T17:18:04.076611Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:18:04.076611Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:18:04.076611Z","label":"CVSS score revised","source":"cvelistv5"}]}