CVE-2026-54168: Tekton Pipelines-as-Code: Unscoped GitHub App installation token allows unauthorized access to private repositories via remote task resolution

When Pipelines-as-Code is configured with a GitHub App installed across multiple repositories, the installation token issued during webhook processing is not scoped to the triggering repository by default. The token retains access to all repositories in the GitHub App installation.

This allows a user with push access to any repository in the installation to craft a PipelineRun with a remote task annotation pointing at a private repository in the same installation:

pipelinesascode.tekton.dev/task: "https://github.com/org/private-repo/blob/main/.tekton/secret-task.yaml"

Pipelines-as-Code resolves and inlines the remote task using the unscoped token, exposing the contents of the private repository’s Tekton definitions. This is a read-only confidentiality breach, no write access is exposed.