`@backstage/backend-common` vulnerable to path traversal through symlinks

Description

Paths checks with the resolveSafeChildPath utility were not exhaustive enough, leading to risk of path traversal vulnerabilities if symlinks can be injected by attackers.

Recommendation

Update the @backstage/backend-common package to the latest compatible version. Followings are version details:

• Affected version(s): **>= 0.20.0, < 0.20.2

  < 0.19.10

  = 0.21.0**

• Patched version(s): **0.20.2

  0.19.10

  0.21.1**

References

• GHSA-2fc9-xpp8-2g9h
• CVE-2024-26150
• CWE-22
• CAPEC-310
• OWASP 2021-A1
• OWASP 2021-A6