XSS in Backstage
CVE-2021-43776
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`.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.007 (50.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 50.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: +0.000
Affected products
- Backstage — versions < 0.4.9
- Linuxfoundation Auth Backend
Weakness classification (CWE)
References
- github.com/backstage/backstage/security/advisories/GHSA-w7fj-336r-vw49 (Third Party Advisory)
- github.com/backstage/backstage/tree/master/plugins/auth-backend (Product, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-43776?
- CVE-2021-43776 is a high-severity vulnerability in Backstage, classified under Cross-site Scripting. CVSS score: 7.4/10. Published 2021-11-26.
- How severe is CVE-2021-43776?
- High severity. CVSS v3 base score is 7.4 out of 10.