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CVE-2021-43776

HIGH
Published 2021-11-26T18:15:10
Actions:

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CVSS Score

V3.1
7.4
/10
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N
Base Score Metrics
Exploitability: N/A Impact: N/A

EPSS Score

v2025.03.14
0.003
probability
of exploitation in the wild

There is a 0.3% chance that this vulnerability will be exploited in the wild within the next 30 days.

Updated: 2025-06-25
Exploit Probability
Percentile: 0.536
Higher than 53.6% of all CVEs

Attack Vector Metrics

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED

Impact Metrics

Confidentiality
HIGH
Integrity
NONE
Availability
NONE

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`.

Available Exploits

No exploits available for this CVE.

Related News

No news articles found for this CVE.

Affected Products

backstage

backstage

Affected Versions:

< 0.4.9

GitHub Security Advisories

Community-driven vulnerability intelligence from GitHub

✓ GitHub Reviewed HIGH

Cross-Site Scripting vulnerability in @backstage/plugin-auth-backend

GHSA-w7fj-336r-vw49

Advisory Details

### Impact This vulnerability 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. ### Patches This is vulnerability is patched in version `0.4.9` of `@backstage/plugin-auth-backend`. ### For more information If you have any questions or comments about this advisory: * Open an issue in the [Backstage repository](https://github.com/backstage/backstage) * Visit our chat, linked to in [Backstage README](https://github.com/backstage/backstage)

Affected Packages

npm @backstage/plugin-auth-backend
ECOSYSTEM: ≥0 <0.4.9

CVSS Scoring

CVSS Score

7.5

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N

References

WEB https://github.com/backstage/backstage/security/advisories/GHSA-w7fj-336r-vw49
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2021-43776
PACKAGE https://github.com/backstage/backstage
WEB https://github.com/backstage/backstage/tree/master/plugins/auth-backend

Advisory provided by GitHub Security Advisory Database. Published: December 1, 2021, Modified: December 1, 2021

References

https://github.com/backstage/backstage/security/advisories/GHSA-w7fj-336r-vw49
https://github.com/backstage/backstage/tree/master/plugins/auth-backend
Published: 2021-11-26T18:15:10
Last Modified: 2024-08-04T04:03:08.688Z
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