CVE-2021-29441

Authentication bypass

View on CVE.org

Published Apr 27, 2021 CVSS 3.1 · 8.6 High EPSS 83.2% KEV · Not listed

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.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

alibaba

nacos

affected

Version	Status	Constraints
`< 1.4.1`	affected	—

Configuration 1 [-]

cpe:2.3:a:alibaba:nacos:*:*:*:*:*:*:*:*

No data.

No data available yet.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

Source	ID	Title
Github GHSA	GHSA-36hp-jr8h-556f	Authentication Bypass

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Changed

Confidentiality Impact High

Integrity Impact None

Availability Impact None

User Interaction None

No CVSS v3.0

Access Vector Network

Access Complexity Low

Authentication None

Confidentiality Impact Partial

Integrity Impact Partial

Availability Impact Partial

This CVE is not in the KEV list.

Exploit prediction score: 83.2% (83.236% probability within 30 days)

Key SSVC decision points have not yet been added.

References

Link	Providers
https://github.com/advisories/GHSA-36hp-jr8h-556f
https://github.com/alibaba/nacos/issues/4701
https://github.com/alibaba/nacos/pull/4703

History

No history.

Subscriptions

Alibaba Nacos

Weaknesses

CWE-290

Sources

CVE record Updated: Aug 3, 2024, 10:02 PM

Status: PUBLISHED
Assigner: GitHub_M
Published: Apr 27, 2021, 8:20 PM
Updated: Aug 3, 2024, 10:02 PM
Reserved: Mar 30, 2021, 12:00 AM

View source JSON

Vulnrichment No data

No data.

NVD Updated: Jun 17, 2026, 3:47 AM

Status: Modified
Published: Apr 27, 2021, 9:15 PM
Modified: Jun 17, 2026, 3:47 AM

View source JSON

Red Hat No data

No data.

OpenCVE enrichment No data

No data.

{"containers": {"cna": {"affected": [{"product": "nacos", "vendor": "alibaba", "versions": [{"status": "affected", "version": "< 1.4.1"}]}], "descriptions": [{"lang": "en", "value": "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."}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.6, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N", "version": "3.1"}}], "problemTypes": [{"descriptions": [{"cweId": "CWE-290", "description": "CWE-290 Authentication Bypass by Spoofing", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"dateUpdated": "2021-04-27T20:20:20.000Z", "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M"}, "references": [{"tags": ["x_refsource_MISC"], "url": "https://github.com/alibaba/nacos/issues/4701"}, {"tags": ["x_refsource_CONFIRM"], "url": "https://github.com/advisories/GHSA-36hp-jr8h-556f"}, {"tags": ["x_refsource_MISC"], "url": "https://github.com/alibaba/nacos/pull/4703"}], "source": {"advisory": "GHSA-36hp-jr8h-556f", "discovery": "UNKNOWN"}, "title": "Authentication bypass", "x_legacyV4Record": {"CVE_data_meta": {"ASSIGNER": "security-advisories@github.com", "ID": "CVE-2021-29441", "STATE": "PUBLIC", "TITLE": "Authentication bypass"}, "affects": {"vendor": {"vendor_data": [{"product": {"product_data": [{"product_name": "nacos", "version": {"version_data": [{"version_value": "< 1.4.1"}]}}]}, "vendor_name": "alibaba"}]}}, "data_format": "MITRE", "data_type": "CVE", "data_version": "4.0", "description": {"description_data": [{"lang": "eng", "value": "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."}]}, "impact": {"cvss": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.6, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N", "version": "3.1"}}, "problemtype": {"problemtype_data": [{"description": [{"lang": "eng", "value": "CWE-290 Authentication Bypass by Spoofing"}]}]}, "references": {"reference_data": [{"name": "https://github.com/alibaba/nacos/issues/4701", "refsource": "MISC", "url": "https://github.com/alibaba/nacos/issues/4701"}, {"name": "https://github.com/advisories/GHSA-36hp-jr8h-556f", "refsource": "CONFIRM", "url": "https://github.com/advisories/GHSA-36hp-jr8h-556f"}, {"name": "https://github.com/alibaba/nacos/pull/4703", "refsource": "MISC", "url": "https://github.com/alibaba/nacos/pull/4703"}]}, "source": {"advisory": "GHSA-36hp-jr8h-556f", "discovery": "UNKNOWN"}}}, "adp": [{"providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-03T22:02:51.975Z"}, "title": "CVE Program Container", "references": [{"tags": ["x_refsource_MISC", "x_transferred"], "url": "https://github.com/alibaba/nacos/issues/4701"}, {"tags": ["x_refsource_CONFIRM", "x_transferred"], "url": "https://github.com/advisories/GHSA-36hp-jr8h-556f"}, {"tags": ["x_refsource_MISC", "x_transferred"], "url": "https://github.com/alibaba/nacos/pull/4703"}]}]}, "cveMetadata": {"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "assignerShortName": "GitHub_M", "cveId": "CVE-2021-29441", "datePublished": "2021-04-27T20:20:20.000Z", "dateReserved": "2021-03-30T00:00:00.000Z", "dateUpdated": "2024-08-03T22:02:51.975Z", "state": "PUBLISHED"}, "dataType": "CVE_RECORD", "dataVersion": "5.1"}

{"affected": [{"affectedData": [{"product": "nacos", "vendor": "alibaba", "versions": [{"status": "affected", "version": "< 1.4.1"}]}], "source": "security-advisories@github.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:alibaba:nacos:*:*:*:*:*:*:*:*", "matchCriteriaId": "167EF403-0A27-4951-83BF-0BE274BBA6B7", "versionEndExcluding": "1.4.1", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "Nacos es una plataforma dise\u00f1ada para el descubrimiento y la configuraci\u00f3n din\u00e1mica de servicios y la gesti\u00f3n de servicios. En Nacos versiones anteriores a 1.4.1, cuando se configura para usar autenticaci\u00f3n (-Dnacos.core.auth.enabled=true), Nacos usa el filtro de servlet AuthFilter para hacer cumplir la autenticaci\u00f3n. Este filtro presenta una backdoor que permite a servidores de Nacos omitir este filtro y, por lo tanto, omitir las comprobaciones de autenticaci\u00f3n. Este mecanismo es basado en el encabezado HTTP del agente de usuario para que pueda falsificarse f\u00e1cilmente. Este problema puede permitir a cualquier usuario llevar a cabo cualquier tarea administrativa en el servidor de Nacos"}], "id": "CVE-2021-29441", "lastModified": "2026-06-17T03:47:38.877", "metrics": {"cvssMetricV2": [{"acInsufInfo": false, "baseSeverity": "HIGH", "cvssData": {"accessComplexity": "LOW", "accessVector": "NETWORK", "authentication": "NONE", "availabilityImpact": "PARTIAL", "baseScore": 7.5, "confidentialityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "vectorString": "AV:N/AC:L/Au:N/C:P/I:P/A:P", "version": "2.0"}, "exploitabilityScore": 10.0, "impactScore": 6.4, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "source": "nvd@nist.gov", "type": "Primary", "userInteractionRequired": false}], "cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.6, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 4.0, "source": "security-advisories@github.com", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2021-04-27T21:15:07.993", "references": [{"source": "security-advisories@github.com", "tags": ["Exploit", "Third Party Advisory"], "url": "https://github.com/advisories/GHSA-36hp-jr8h-556f"}, {"source": "security-advisories@github.com", "tags": ["Exploit", "Third Party Advisory"], "url": "https://github.com/alibaba/nacos/issues/4701"}, {"source": "security-advisories@github.com", "tags": ["Patch", "Third Party Advisory"], "url": "https://github.com/alibaba/nacos/pull/4703"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Exploit", "Third Party Advisory"], "url": "https://github.com/advisories/GHSA-36hp-jr8h-556f"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Exploit", "Third Party Advisory"], "url": "https://github.com/alibaba/nacos/issues/4701"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch", "Third Party Advisory"], "url": "https://github.com/alibaba/nacos/pull/4703"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-290"}], "source": "security-advisories@github.com", "type": "Secondary"}, {"description": [{"lang": "en", "value": "CWE-290"}], "source": "nvd@nist.gov", "type": "Primary"}]}