Path Traversal in @backstage/plugin-scaffolder-backend

published 2021-11-29 4 y ago modified 2026-07-08 4 mo ago also GHSA-mg3m-f475-28hv , EUVD-2021-2554

cvss: 8.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 1.2%; EPSS 1.2% chance of exploitation in 30 days, percentile 69%
public exploits: 0; none known

@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.

Patch / fix

fixed in 2 links 1

npm @backstage/plugin-scaffolder-backend 0.15.14
linuxfoundation backstage 0.15.14

github.com/backstage/backstage@f9352ab commit

Exploit prediction

1.25% chance of exploitation in the next 30 days, higher than 69% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L
NVD	3.1	8.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L
NVD	2.0	5.5	AV:N/AC:L/Au:S/C:N/I:P/A:P
GitHub	3.1	8.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L

Affected packages

ecosystem	package	affected	fixed in
npm	@backstage/plugin-scaffolder-backend	<0.15.14	0.15.14

Affected products

backstage backstage

Classification

Weakness

CWE-22 Improper Limitation of a Pathname to a Restricted Directory

References

github.com /backstage/backstage/commit/f9352ab606367cd9efc6ff048915c70ed3013b7f
web, patch, third-party-advisory
github.com /backstage/backstage/security/advisories/GHSA-mg3m-f475-28hv
web, third-party-advisory
nvd.nist.gov /vuln/detail/CVE-2021-43783
advisory
github.com /backstage/backstage
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary