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CVE-2026-106491

MEDIUM 6.4

Published 2026-10-06 · Last modified 2026-10-07

Backstage is an open framework for building developer portals. Prior to 0.6.17, the @backstage/plugin-proxy-backend package is affected by improper input validation in proxy-backend. An authenticated Backstage user could craft a request URL that causes the proxy-backend to forward the request to a path outside the configured base path on the target server. This is limited to target servers already configured as proxy endpoints and requires Backstage authentication by default. This issue is fixed in version 0.6.17.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.3%chance of exploitation in 30 days · 20th percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

6.4CVSS 3.1 · MEDIUM

  • ConfidentialityLow
  • IntegrityLow
  • AvailabilityNone

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ⚠Privileges: Requires a low-privilege account
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

Search for new PoCs

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Tracked sources are checked daily for recent CVEs, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.

Data snapshot:

Affected

Vendors Backstage @Backstage Linuxfoundation

Products Backstage Plugin Proxy Backend Backstage\/Plugin Proxy Backend

Weakness (CWE)

  • CWE-20: : Improper Input Validation
  • CWE-22: : Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

References and research data (JSON)

Packages and version ranges

Each advisory describes its own package and affected ranges. A boundary applies to that range; it is not a universal upgrade recommendation.

  • @backstage/plugin-proxy-backend npm

    pkg:npm/%40backstage/plugin-proxy-backend

    SEMVER range
    • All earlier versions (introduced 0)
    • Fixed boundary (excluded): 0.6.17
    Additional upstream package constraints
    {
  "database": {
    "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-9ghw-48h5-v2w5/GHSA-9ghw-48h5-v2w5.json"
  }
}
    GitHub Advisory Database · GHSA-9ghw-48h5-v2w5 · Updated 2026-10-07T18:15:11.766501419Z

Vendor product assessments

  • rhdh/rhdh-hub-rhel9 as a component of Red Hat Developer Hub · known affected

    Vendor assessment for this product only.

    pkg:oci/rhdh-hub-rhel9?repository_url=registry.redhat.io/rhdh/rhdh-hub-rhel9

    • workaround: To mitigate this issue, deploy an upstream reverse proxy or Web Application Firewall (WAF) in front of the Backstage / Red Hat Developer Hub backend configured to normalize incoming URI paths and block path traversal sequences before requests reach the application.
    • none available: Fix deferred
    Red Hat · CVE-2026-106491 · Updated 2026-10-09T08:55:27+00:00
  • ansible-automation-platform/automation-portal as a component of Self-service automation portal 2 · known affected

    Vendor assessment for this product only.

    pkg:oci/automation-portal?repository_url=registry.redhat.io/ansible-automation-platform/automation-portal

    • workaround: To mitigate this issue, deploy an upstream reverse proxy or Web Application Firewall (WAF) in front of the Backstage / Red Hat Developer Hub backend configured to normalize incoming URI paths and block path traversal sequences before requests reach the application.
    • none available: Fix deferred
    Red Hat · CVE-2026-106491 · Updated 2026-10-09T08:55:27+00:00
  • ansible-automation-platform/bootc-automation-portal-rhel9 as a component of Self-service automation portal 2 · known affected

    Vendor assessment for this product only.

    pkg:oci/bootc-automation-portal-rhel9?repository_url=registry.redhat.io/ansible-automation-platform/bootc-automation-portal-rhel9

    • workaround: To mitigate this issue, deploy an upstream reverse proxy or Web Application Firewall (WAF) in front of the Backstage / Red Hat Developer Hub backend configured to normalize incoming URI paths and block path traversal sequences before requests reach the application.
    • none available: Fix deferred
    Red Hat · CVE-2026-106491 · Updated 2026-10-09T08:55:27+00:00

Known Affected Software Configurations

VendorProductVersion range
LinuxfoundationBackstage\/Plugin Proxy Backend< 0.6.17
LinuxfoundationBackstage< 1.54.6

All CVSS metrics

  • MEDIUM 6.4 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
  • MEDIUM 6.4 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

References

Patches & mitigations

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS