CVE-2021-43776 : Backstage is an open platform for building developer portals. In affected versio

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`.

Published 2021-11-26 19:15:08

Updated 2021-11-30 19:11:15

Source GitHub, Inc.

View at NVD, CVE.org

Vulnerability category: Cross site scripting (XSS)

Products affected by CVE-2021-43776

Linuxfoundation » Auth Backend » For Node.js
Versions before (<) 0.4.9
cpe:2.3:a:linuxfoundation:auth_backend:*:*:*:*:*:node.js:*:*
Matching versions

Exploit prediction scoring system (EPSS) score for CVE-2021-43776

EPSS FAQ

0.31%

Probability of exploitation activity in the next 30 days EPSS Score History

~ 54 %

Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2021-43776

Base Score	Base Severity	CVSS Vector	Exploitability Score	Impact Score	Score Source
4.3	MEDIUM	AV:N/AC:M/Au:N/C:N/I:P/A:N	8.6	2.9	NIST
Access Vector: Network Access Complexity: Medium Authentication: None Confidentiality Impact: None Integrity Impact: Partial Availability Impact: None
6.1	MEDIUM	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N	2.8	2.7	NIST
Attack Vector: Network Attack Complexity: Low Privileges Required: None User Interaction: Required Scope: Changed Confidentiality: Low Integrity: Low Availability: None
7.4	HIGH	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N	2.8	4.0	GitHub, Inc.
Attack Vector: Network Attack Complexity: Low Privileges Required: None User Interaction: Required Scope: Changed Confidentiality: High Integrity: None Availability: None

CWE ids for CVE-2021-43776

CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Assigned by: security-advisories@github.com (Primary)

References for CVE-2021-43776

https://github.com/backstage/backstage/tree/master/plugins/auth-backend

backstage/plugins/auth-backend at master · backstage/backstage · GitHub
Product;Third Party Advisory
https://github.com/backstage/backstage/security/advisories/GHSA-w7fj-336r-vw49

Reflected XSS vulnerability in @backstage/plugin-auth-backend · Advisory · backstage/backstage · GitHub
Third Party Advisory

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Vulnerability Details : CVE-2021-43776

Products affected by CVE-2021-43776

Exploit prediction scoring system (EPSS) score for CVE-2021-43776

CVSS scores for CVE-2021-43776

CWE ids for CVE-2021-43776

References for CVE-2021-43776