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No exploitation reportedFix available

CVE-2021-43783

No exploitation reported by the sources we read.

  • Published2021-11-29
  • Fixed in0.15.14
  • WeaknessCWE-22

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

@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.

Timeline

dates in UTC
  1. 2021-11-2920:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-43783?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-43783?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Linuxfoundation backstage
BranchAffectedFixed in
0.15< 0.15.140.15.14

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Linuxfoundation backstage to 0.15.14

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CNACVSS 3.18.5read 2026-10-23
  • NVDCVSS 3.18.5read 2026-10-23
  • NVDCVSS 2.05.5read 2026-10-23
  • CNAweakness (CWE)CWE-22read 2026-10-23
  • NVDweakness (CWE)CWE-22read 2026-10-23
  • FIRST EPSSEPSS score1.2 %2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L
Published
2021-11-29
Last Modified
2026-06-17
NVD status
Undergoing Analysis

Frequently asked questions

What is CVE-2021-43783?

@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.

Is CVE-2021-43783 actively exploited?

Active exploitation of CVE-2021-43783 has not been confirmed. Its EPSS score was 1.2% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-43783?

CVE-2021-43783 has a CVSS v3 base score of 8.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L.

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