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@backstage/plugin-scaffolder-backend Vulnerable to Potential Session Token Exfiltration via Log Redaction Bypass

Low severity GitHub Reviewed Published Mar 4, 2026 in backstage/backstage • Updated Mar 9, 2026

Package

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

Affected versions

<= 3.1.3

Patched versions

3.1.4

Description

Impact

A malicious scaffolder template can bypass the log redaction mechanism to exfiltrate secrets provided run through task event logs.

The attack requires:

  • The ability to register a template in the catalog
  • A victim who executes the malicious template

Patches

Patched in @backstage/plugin-scaffolder-backend version 3.1.4

Workarounds

  • Implement a custom permission policy that restricts scaffolder.task.read so users can only read their own task logs
  • Restrict who can register templates in the catalog to trusted users only

Resources

References

@benjdlambert benjdlambert published to backstage/backstage Mar 4, 2026
Published to the GitHub Advisory Database Mar 5, 2026
Reviewed Mar 5, 2026
Published by the National Vulnerability Database Mar 7, 2026
Last updated Mar 9, 2026

Severity

Low

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
High
Privileges required
High
User interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
None
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:H/PR:H/UI:R/S:U/C:L/I:N/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.
(7th percentile)

Weaknesses

Insertion of Sensitive Information into Log File

The product writes sensitive information to a log file. Learn more on MITRE.

CVE ID

CVE-2026-29184

GHSA ID

GHSA-8qp7-fhr9-fw53

Source code

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