VULNERABILITY INTELLIGENCE
CVE-2021-43776
CVSS score7.4 HIGH
EPSS probability0.68%
CISA KEVNot currently listed
Published2021-11-26
Last modified2026-06-17
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N
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`.
Weakness classification
- security-advisories@github.com: CWE-79
Primary references
- security-advisories@github.com — Third Party Advisory
- security-advisories@github.com — Product, Third Party Advisory
- af854a3a-2127-422b-91ae-364da2661108 — Third Party Advisory
- af854a3a-2127-422b-91ae-364da2661108 — Product, Third Party Advisory