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Backstage: Sensitive information exposure in Scaffolder

Critical severity GitHub Reviewed Published Aug 28, 2026 in backstage/backstage • Updated Oct 7, 2026

Package

npm @backstage/plugin-scaffolder-backend (npm)

Affected versions

< 3.3.1
>= 3.4.0, < 3.4.1
>= 4.0.0, < 4.0.3
>= 4.0.4, < 4.1.0

Patched versions

3.3.1
3.4.1
4.0.3
4.1.0

Description

Impact

An authenticated Backstage user who can read another user's Scaffolder task may receive internal execution data. In deployments where that data contains credentials for an external service, this may permit disclosure and unauthorized changes in that external service.

Patches

Patched in @backstage/plugin-scaffolder-backend version 4.1.0

Workarounds

  • Configure scaffolder.task.read with the isTaskOwner condition so users can only read tasks they created.
  • Restrict affected integrations and workflows to trusted operators until an upgrade is available.

References

@freben freben published to backstage/backstage Aug 28, 2026
Published by the National Vulnerability Database Oct 6, 2026
Published to the GitHub Advisory Database Oct 7, 2026
Reviewed Oct 7, 2026
Last updated Oct 7, 2026

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(40th percentile)

Weaknesses

Exposure of Sensitive Information to an Unauthorized Actor

The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Learn more on MITRE.

Insertion of Sensitive Information Into Sent Data

The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor. Learn more on MITRE.

CVE ID

CVE-2026-106501

GHSA ID

GHSA-g2v8-7jhw-pp8p

Source code

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