CVE-2026-106458: Backstage: Inconsistent repository filtering in Bitbucket Server catalog event updates
Impact
Deployments using event-driven updates in the Bitbucket Server catalog provider may ingest catalog locations from repositories that are excluded by the provider's configured project, repository, or archived-repository filters.
An authenticated Bitbucket Server user who can push to a filtered-out repository that remains readable by the configured Backstage integration can trigger a legitimate repository event. The affected event path may then add a Location for that repository even though scheduled discovery excludes it. This can cause catalog entities and metadata to be ingested from a repository that the operator did not intend to trust.
Deployments that do not enable event support for the Bitbucket Server catalog provider, do not configure repository filters, or whose integration credentials cannot read the filtered-out repositories are not affected.
Patches
Upgrade @backstage/plugin-catalog-backend-module-bitbucket-server to version 0.5.15 or later. The fixed package is available in Backstage v1.55.0.
Workarounds
- Disable event-driven updates for the Bitbucket Server catalog provider and rely on scheduled discovery until the patched package is deployed. - Restrict the configured Bitbucket Server integration credentials so that they cannot read repositories that must remain outside the catalog trust boundary.
Other sources
Backstage is an open framework for building developer portals. From 0.4.0 until 0.5.15, the @backstage/plugin-catalog-backend-module-bitbucket-server package is affected by inconsistent repository filtering in bitbucket server catalog event updates. Deployments using event-driven updates in the Bitbucket Server catalog provider may ingest catalog locations from repositories that are excluded by the provider's configured project, repository, or archived-repository filters. An authenticated Bitbucket Server user who can push to a filtered-out repository that remains readable by the configured Backstage integration can trigger a legitimate repository event. The affected event path may then add a Location for that repository even though scheduled discovery excludes it. This issue is fixed in version 0.5.15.
— NVD
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
npm/@backstage/plugin-catalog-backend-module-bitbucket-serverto a version that resolves this vulnerability.Fixed in 0.5.15 - Upgrade
Upgrade
@backstage/plugin-catalog-backend-module-bitbucket-serverto a version that resolves this vulnerability.Fixed in 0.5.15 - Configuration
Disable event-driven updates and rely on scheduled discovery until the patched package is deployed.
Bitbucket Server catalog provider event-driven updates = disabled - Compensating control
Restrict the configured Bitbucket Server integration credentials so they cannot read repositories that must remain outside the catalog trust boundary.
Event History
Frequently Asked Questions
Which deployments are exposed to this issue?
Deployments using event-driven updates in the Bitbucket Server catalog provider are affected if the configured Backstage integration can read a repository that is excluded by the provider's project, repository, or archived-repository filters. Scheduled discovery continues to exclude those repositories, but the event-processing path may not.
What access does an attacker need?
An attacker needs an authenticated Bitbucket Server account with permission to push to a filtered-out repository. That repository must still be readable by the Bitbucket Server integration configured in Backstage, and the attacker can then trigger a legitimate repository event.
What is the practical impact of successful exploitation?
A repository excluded from catalog discovery filters can be added to the Backstage catalog as a Location through an event update. This bypasses the intended filtering for the event-driven ingestion path.
How can this be remediated?
Upgrade @backstage/plugin-catalog-backend-module-bitbucket-server to version 0.5.15, which fixes the issue. The affected versions start at 0.4.0 and end before 0.5.15.
What can be done if an upgrade cannot be applied immediately?
Avoid using event-driven updates in the Bitbucket Server catalog provider, or ensure the Backstage integration cannot read repositories that are excluded by its configured filters. This prevents events from filtered-out but integration-readable repositories from reaching the affected path.