High severity7.4NVD Advisory· Published Nov 26, 2021· Updated Jun 17, 2026
CVE-2021-43776
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. This is vulnerability is patched in version 0.4.9 of @backstage/plugin-auth-backend.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
@backstage/plugin-auth-backendnpm | < 0.4.9 | 0.4.9 |
Affected products
3- cpe:2.3:a:linuxfoundation:auth_backend:*:*:*:*:*:node.js:*:*Range: <0.4.9
Patches
Vulnerability mechanics
References
4- github.com/advisories/GHSA-w7fj-336r-vw49ghsaADVISORY
- github.com/backstage/backstage/security/advisories/GHSA-w7fj-336r-vw49nvdThird Party AdvisoryWEB
- github.com/backstage/backstage/tree/master/plugins/auth-backendnvdProductThird Party AdvisoryWEB
- nvd.nist.gov/vuln/detail/CVE-2021-43776ghsaADVISORY
News mentions
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