{"api_version":"1","generated_at":"2026-07-24T23:37:57+00:00","cve":"CVE-2021-43776","urls":{"html":"https://cve.report/CVE-2021-43776","api":"https://cve.report/api/cve/CVE-2021-43776.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2021-43776","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-43776"},"summary":{"title":"CVE-2021-43776","description":"Backstage is an open platform for building developer portals. In affected versions the auth-backend plugin allows a malicious actor to trick another user into visiting a vulnerable URL that executes an XSS attack. This attack can potentially allow the attacker to exfiltrate access tokens or other secrets from the user's browser. The default CSP does prevent this attack, but it is expected that some deployments have these policies disabled due to incompatibilities. 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This is vulnerability is patched in version `0.4.9` of `@backstage/plugin-auth-backend`."}]},"impact":{"cvss":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":7.4,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N","version":"3.1"}},"problemtype":{"problemtype_data":[{"description":[{"lang":"eng","value":"CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')"}]}]},"references":{"reference_data":[{"name":"https://github.com/backstage/backstage/security/advisories/GHSA-w7fj-336r-vw49","refsource":"CONFIRM","url":"https://github.com/backstage/backstage/security/advisories/GHSA-w7fj-336r-vw49"},{"name":"https://github.com/backstage/backstage/tree/master/plugins/auth-backend","refsource":"MISC","url":"https://github.com/backstage/backstage/tree/master/plugins/auth-backend"}]},"source":{"advisory":"GHSA-w7fj-336r-vw49","discovery":"UNKNOWN"}},"nvd":{"publishedDate":"2021-11-26 19:15:00","lastModifiedDate":"2021-11-30 19:11:00","problem_types":["CWE-79"],"metrics":{"baseMetricV3":{"cvssV3":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"CHANGED","confidentialityImpact":"LOW","integrityImpact":"LOW","availabilityImpact":"NONE","baseScore":6.1,"baseSeverity":"MEDIUM"},"exploitabilityScore":2.8,"impactScore":2.7},"baseMetricV2":{"cvssV2":{"version":"2.0","vectorString":"AV:N/AC:M/Au:N/C:N/I:P/A:N","accessVector":"NETWORK","accessComplexity":"MEDIUM","authentication":"NONE","confidentialityImpact":"NONE","integrityImpact":"PARTIAL","availabilityImpact":"NONE","baseScore":4.3},"severity":"MEDIUM","exploitabilityScore":8.6,"impactScore":2.9,"acInsufInfo":false,"obtainAllPrivilege":false,"obtainUserPrivilege":false,"obtainOtherPrivilege":false,"userInteractionRequired":true}},"configurations":{"CVE_data_version":"4.0","nodes":[{"operator":"OR","children":[],"cpe_match":[{"vulnerable":true,"cpe23Uri":"cpe:2.3:a:linuxfoundation:auth_backend:*:*:*:*:*:node.js:*:*","versionEndExcluding":"0.4.9","cpe_name":[]}]}]}},"legacy_mitre":{"record":{"CveYear":"2021","CveId":"43776","Ordinal":"221378","Title":"CVE-2021-43776","CVE":"CVE-2021-43776","Year":"2021"},"notes":[{"CveYear":"2021","CveId":"43776","Ordinal":"1","NoteData":"** RESERVED ** This candidate has been reserved by an organization or individual that will use it when announcing a new security problem. When the candidate has been publicized, the details for this candidate will be provided.","Type":"Description","Title":null}]}}}