backstage backstage CVE-2021-43783 in Backstage and Linux Foundation Products
Published on November 29, 2021

Path Traversal in @backstage/plugin-scaffolder-backend

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@backstage/plugin-scaffolder-backend is the backend for the default Backstage software templates. In affected versions a malicious actor with write access to a registered scaffolder template is able to manipulate the template in a way that writes files to arbitrary paths on the scaffolder-backend host instance. This vulnerability can in some situation also be exploited through user input when executing a template, meaning you do not need write access to the templates. This method will not allow the attacker to control the contents of the injected file however, unless the template is also crafted in a specific way that gives control of the file contents. This vulnerability is fixed in version `0.15.14` of the `@backstage/plugin-scaffolder-backend`. This attack is mitigated by restricting access and requiring reviews when registering or modifying scaffolder templates.

Github Repository NVD

Vulnerability Analysis

CVE-2021-43783 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, a high impact on integrity, and a small impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
LOW
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
NONE
Integrity Impact:
HIGH
Availability Impact:
LOW

Weakness Type

What is a Directory traversal Vulnerability?

The software uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the software does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

CVE-2021-43783 has been classified to as a Directory traversal vulnerability or weakness.


Products Associated with CVE-2021-43783

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Backstage
 
Linux Foundation Backstage
 

Affected Versions

backstage Version < 0.15.14 is affected by CVE-2021-43783

Vulnerable Packages

The following package name and versions may be associated with CVE-2021-43783

Package Manager Vulnerable Package Versions Fixed In
npm @backstage/plugin-scaffolder-backend < 0.15.14 0.15.14

Exploit Probability

EPSS
0.35%
Percentile
57.34%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.