CVE-2021-43783Network attack vector

Arbitrary file writes via unsafe path resolution

Published Nov 29, 2021 · Updated Aug 4, 2024

Path traversal in Backstage Scaffolder Backend before 0.15.14 allows remote authenticated users to write files outside the workspace. The fetch:template action passes rendered, template-controlled output paths to path.resolve, which resolves traversal segments beyond the intended output directory. Template write access is normally required, but crafted templates can expose the path through execution input; file contents are attacker-controlled only when the template supplies them.

CVSS severity8.5
High
EPSS probability1.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Backstage Scaffolder Backend before 0.15.14 allows remote authenticated users to write files outside the workspace. The fetch:template action passes rendered, template-controlled output paths to path.resolve, which resolves traversal segments beyond the intended output directory. Template write access is normally required, but crafted templates can expose the path through execution input; file contents are attacker-controlled only when the template supplies them.

The record

CVE
CVE-2021-43783
Published
Nov 29, 2021
Updated
Aug 4, 2024
Vendor
Backstage
Product
Backstage
Classifications
CWE-22, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 29, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.15.14

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Backstage · Backstageversion=< 0.15.14

Published CVSS scores

8.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L
5.5NIST NVDAV:N/AC:L/Au:S/C:N/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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