CVE-2021-43783

What it is

@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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of data tampering.

Exploit odds

1.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-11-29 20:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 04:11 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.2% in the next 30 days (EPSS).
• Severity: 8.5 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-11-29 20:15 UTC

Last modified

2026-06-17 04:11 UTC

Exploit probability

1.2% · EPSS, next 30 days

Weakness

CWE-22 · Path traversal

Record status

Undergoing Analysis

Affected

• Linuxfoundation Backstage < 0.15.14

Attack profile CVSS 3.1 · 8.5

Attack vector

Network

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Changed

Confidentiality

None

Integrity

High

Availability

Low

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-43783.md and follow it. Check whether this project is affected by CVE-2021-43783. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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