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Fencer Intel
high 8.5

CVE-2021-43783 json

Path Traversal in @backstage/plugin-scaffolder-backend

published 4y ago modified 4mo 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

Summary

@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

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

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Exploit prediction

1.25% chance of exploitation in the next 30 days, higher than 69% of all scored CVEs (FIRST EPSS, 2026-11-09).

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

Sources

Fencer Intel 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.