# Backstage has sensitive information exposure in scaffolder task logs

Advisory record · `GHSA-4xvq-3m68-h444`

- **Identifiers:** `GHSA-4xvq-3m68-h444` · `CVE-2026-106504`
- **State:** Confirmed
- **Severity:** CVSS 6.5 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-532](https://cwe.mitre.org/data/definitions/532.html)
- **Tags:** [Information disclosure](https://agentprime.io/advisories/tag/info-disclosure.md)
- **Published:** 7 Oct 2026
- **Updated:** 7 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 7 Oct 2026, 16:24 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `@backstage/plugin-scaffolder-backend` (npm): affected `<4.1.0`; fixed in `4.1.0`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> An authenticated user who can create and read scaffolder tasks may be able to see sensitive values in task logs of @backstage/plugin-scaffolder-backend versions before 4.1.0. Exploitation requires a denied action whose input contains such a value, and deployments with restrictive action permissions and affected templates are the ones at risk. Upgrade to @backstage/plugin-scaffolder-backend 4.1.0 or later; until then, restrict scaffolder task creation and log reading to trusted users and avoid putting centrally managed sensitive values in inputs to actions that may be denied.

Written 31 Oct 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 6.5 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0026, the 17th percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 13:33 UTC: First seen by agentprime
- 31 Oct 2026, 13:33 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-4xvq-3m68-h444)

## Sources

- [GitHub Advisory Database: GHSA-4xvq-3m68-h444](https://github.com/advisories/GHSA-4xvq-3m68-h444)
- [OSV: GHSA-4xvq-3m68-h444](https://osv.dev/vulnerability/GHSA-4xvq-3m68-h444)
- <https://github.com/backstage/backstage/security/advisories/GHSA-4xvq-3m68-h444>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-106504>
- <https://github.com/backstage/backstage/commit/3eb3dc59eb0da0deccd532f19eb460bb452c9efb>
- <https://github.com/backstage/backstage>
- <https://github.com/backstage/backstage/releases/tag/v1.54.6>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-4xvq-3m68-h444>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-4xvq-3m68-h444/>. Everything for agents: <https://agentprime.io/llms.txt>.