# CVE-2026-106499: Backstage: Secret-derived values may be exposed in scaffolder task logs


- **Severity:** Medium 4.9 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 6 Oct 2026
- **Updated:** 7 Oct 2026
- **Also known as:** GHSA-mfvq-x7vr-rgqg

## What is CVE-2026-106499?

CVE-2026-106499 is a medium-severity vulnerability in Linuxfoundation Backstage, published on 6 Oct 2026. 

### Official description

Backstage is an open framework for building developer portals. Prior to 4.1.0, the @backstage/plugin-scaffolder-backend package could expose secret-derived values in Scaffolder task logs. Deployments that configure sensitive scaffolder.defaultEnvironment.secrets and allow an attacker to create or modify Scaffolder templates are affected. A template author could cause secret-derived values used during template iteration to be persisted and exposed to users who can access the resulting task logs. This issue is fixed in version 4.1.0.

Weakness: CWE-532 (Insertion of Sensitive Information into Log File)

## Which versions are affected by CVE-2026-106499?

2 open source packages ship an affected version, including @backstage/plugin-scaffolder-backend. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@backstage/plugin-scaffolder-backend` | npm | All versions | 4.1.0 |
| `@backstage/plugin-scaffolder-backend` | npm | All versions | 4.1.0 |

Products: Linuxfoundation Backstage, Linuxfoundation Backstage\/Plugin-Scaffolder-Backend.

## How do I fix CVE-2026-106499?

Upgrade @backstage/plugin-scaffolder-backend to 4.1.0 or later.

## Is CVE-2026-106499 being exploited?

There is no known exploitation of CVE-2026-106499 in the wild and no public exploit code.

## Other vulnerabilities in Linuxfoundation Backstage

- [CVE-2026-106501](https://insights.sbomify.com/CVE-2026-106501/): Backstage: Sensitive information exposure in Scaffolder (critical 9.6)
- [CVE-2026-106558](https://insights.sbomify.com/CVE-2026-106558/): Backstage: Improper validation of TechDocs MkDocs configuration (high 8.8)
- [CVE-2026-88064](https://insights.sbomify.com/CVE-2026-88064/): Backstage: Improper input validation in TechDocs MkDocs configuration (high 8.8)
- [CVE-2026-106459](https://insights.sbomify.com/CVE-2026-106459/): Backstage: Improper input validation in Sentry scaffolder actions (high 8.5)
- [CVE-2026-106486](https://insights.sbomify.com/CVE-2026-106486/): Backstage: Improper filesystem validation in Bitbucket pull-request scaffolder actions (high 8.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-106499 and fix it if it is affected.

What it is: CVE-2026-106499 is a medium-severity vulnerability in Linuxfoundation Backstage, published on 6 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-106499 in the wild and no public exploit code.

Affected packages and fixed versions:
- @backstage/plugin-scaffolder-backend (npm): affected all versions; fixed in 4.1.0
- @backstage/plugin-scaffolder-backend (npm): affected all versions; fixed in 4.1.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-106499/ (Markdown: https://insights.sbomify.com/CVE-2026-106499/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-106499
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-106499
- OSV: https://osv.dev/vulnerability/CVE-2026-106499

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-106499/
Summaries are generated and may contain mistakes; the official description above is the record.