{"basis":"claimed","id":"CVE-2021-29441","name":"Authentication bypass","vendorProject":"alibaba","product":"nacos","publishedAt":"2021-04-27","cvss":{"score":8.6,"severity":"HIGH","version":"3.1"},"exploited":null,"epss":{"score":0.83246,"percentile":0.9968,"date":"2026-11-02"},"coverage":{"cloudflare":{"status":"no_history","firstOn":null,"daysToRule":null},"aws":{"status":"none","firstOn":null,"daysToRule":null},"azure":{"status":"none","firstOn":null,"daysToRule":null},"google":{"status":"no_history","firstOn":null,"daysToRule":null},"fastly":{"status":"no_history","firstOn":null,"daysToRule":null},"f5":{"status":"rule","firstOn":"2024-03-12","daysToRule":1050},"akamai":{"status":"no_source","firstOn":null,"daysToRule":null},"crs":{"status":"no_history","firstOn":null,"daysToRule":null}},"title":"Authentication bypass","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.","cwes":["CWE-290"],"vendors":[{"vendor":"cloudflare","status":"no_history","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"aws","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"azure","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"google","status":"no_history","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"fastly","status":"no_history","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"f5","status":"rule","basis":"claimed","firstOn":"2024-03-12","firstIsNew":true,"daysToRule":1050,"daysAtMost":null,"freePlan":false,"claims":[{"id":"d320a68dd0189f6267633f3333bcda472a7ecbcb7bdc69d75838bd901283fc24","cve_id":"CVE-2021-29441","vendor":"f5","product":"Attack signatures","rule_id":"200013077","rule_name":"Nacos AuthFilter Authentication Bypass","change":"new","default_action":null,"published_on":"2024-03-12","source_url":"https://docs.cloud.f5.com/docs-v2/platform/changelogs/security-details-changelog","source_title":"F5 Distributed Cloud attack signatures changelog","excerpt":"Added: signature 200013077 \"Nacos AuthFilter Authentication Bypass\" (Authentication/Authorization Attacks, risk High), systems: Java Servlets/JSP. References: CVE-2021-29441.","first_seen_at":"2026-11-02T21:00:27.754Z"}]},{"vendor":"akamai","status":"no_source","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"crs","status":"no_history","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]}],"updatedAt":"2026-11-02T21:05:18.107Z","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","ssvc":null,"measured":[{"engineId":"owasp-crs","engineName":"OWASP Core Rule Set","engineVersion":"4.25.0","runtime":"Coraza v3.8.1","config":"paranoia level 1, anomaly threshold 5, default CRS settings","ranAt":"2026-11-02T13:02:57.000Z","verdict":"passed","templateId":"CVE-2021-29441","templatePath":"http/cves/2021/CVE-2021-29441.yaml","requests":2,"blockedRequests":0,"rules":[],"note":"","requestDetail":[{"method":"POST","path":"/nacos/v1/cs/configs?…","status":200,"blocked":false,"rules":[]},{"method":"POST","path":"/nacos/v1/cs/configs?…","status":200,"blocked":false,"rules":[]}]},{"engineId":"owasp-crs","engineName":"OWASP Core Rule Set","engineVersion":"4.25.0","runtime":"Coraza v3.8.1","config":"paranoia level 2, anomaly threshold 5, default CRS settings","ranAt":"2026-11-02T13:03:28.000Z","verdict":"passed","templateId":"CVE-2021-29441","templatePath":"http/cves/2021/CVE-2021-29441.yaml","requests":2,"blockedRequests":0,"rules":[],"note":"","requestDetail":[{"method":"POST","path":"/nacos/v1/cs/configs?…","status":200,"blocked":false,"rules":[]},{"method":"POST","path":"/nacos/v1/cs/configs?…","status":200,"blocked":false,"rules":[]}]}],"social":{"total":0,"first_seen":null,"daily":[{"day":"2026-10-21","posts":0},{"day":"2026-10-22","posts":0},{"day":"2026-10-23","posts":0},{"day":"2026-10-24","posts":0},{"day":"2026-10-25","posts":0},{"day":"2026-10-26","posts":0},{"day":"2026-10-27","posts":0},{"day":"2026-10-28","posts":0},{"day":"2026-10-29","posts":0},{"day":"2026-10-30","posts":0},{"day":"2026-10-31","posts":0},{"day":"2026-11-01","posts":0},{"day":"2026-11-02","posts":0},{"day":"2026-11-03","posts":0}],"top_posts":[],"exploit_repositories":[]}}