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CVE-2026-106498

Backstage: Improper URL validation in catalog entity placeholder resolution

HIGH
7.7
CVSS Score
Published: October 6, 2026 at 09:23 PM UTC
Updated: October 16, 2026 at 03:22 PM UTC
4 products affected across 2 vendorsBackstageBackstage Plugin Catalog BackendBackstage

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Severity
HIGH7.7
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

Description

Backstage is an open framework for building developer portals. Prior to 3.5.1, 3.6.2, 3.7.2, 3.8.2 and 3.9.1, the @backstage/plugin-catalog-backend package is affected by improper url validation in catalog entity placeholder resolution. An authenticated Backstage user could craft a catalog entity with placeholder directives that reference resources outside the entity's source repository. Under certain configurations, this could allow access to data not intended to be available to the user. This issue is fixed in versions 3.5.1, 3.6.2, 3.7.2, 3.8.2 and 3.9.1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Backstage· Linuxfoundation
95%
v < 1.49.61.50.0 ≤ v < 1.50.51.51.0 ≤ v < 1.51.31.52.0 ≤ v < 1.53.21.54.0 ≤ v < 1.54.6
Backstage Plugin Catalog Backend· Linuxfoundationnpm
95%
v < 3.5.13.6.0 ≤ v < 3.6.23.7.0 ≤ v < 3.7.23.8.0 ≤ v < 3.8.23.9.0 ≤ v < 3.9.1
Backstage· Backstage
90%
v < 1.49.6>= 1.50.0-next.0, < 1.50.5>= 1.51.0-next.0, < 1.51.3>= 1.52.0-next.0, < 1.53.2>= 1.54.0-next.0, < 1.54.6
Plugin Catalog Backend· Backstage
90%
v < 3.5.1>= 3.6.0, < 3.6.2>= 3.7.0, < 3.7.2>= 3.8.0, < 3.8.2>= 3.9.0, < 3.9.1

References (11)

x_refsource_CONFIRMMitigationVendor Advisory
Source: cverecord
https://github.com/backstage/backstage/security/advisories/GHSA-qgvj-qcf8-xq73
x_refsource_MISCPatch
Source: cverecord
https://github.com/backstage/backstage/commit/0b0f6fc89b4eb4872c76a498abbe1dc65998bb6e
x_refsource_MISCPatch
Source: cverecord
https://github.com/backstage/backstage/commit/286bfc1f9cc3608a073b41016be302785be385d1
x_refsource_MISCPatch
Source: cverecord
https://github.com/backstage/backstage/commit/61a10f19926aeda7f4a32de48d733e6710584634
x_refsource_MISCPatch
Source: cverecord
https://github.com/backstage/backstage/commit/99729e925fd2bd40ba210022351a0ee6318e6197
x_refsource_MISCPatch
Source: cverecord
https://github.com/backstage/backstage/commit/e786ac309ed2d775daf2309393c015c43902d6f6
x_refsource_MISCPatchRelease Notes
Source: cverecord
https://github.com/backstage/backstage/releases/tag/v1.49.6
x_refsource_MISCPatchRelease Notes
Source: cverecord
https://github.com/backstage/backstage/releases/tag/v1.50.5

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.7HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-863CWE-918

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