Pipelines-as-Code EUVD-2026-78586

Exploitation requires all of the following: (1) Pipelines-as-Code must be configured with a GitHub App installed across multiple repositories or org-wide - single-repository installations are not vulnerable; (2) the attacker must hold push access (write permission) to at least one repository in that GitHub App installation; (3) a target private repository containing Tekton task YAML must exist within the same GitHub App installation; (4) the attacker must be able to trigger webhook processing, which occurs naturally via a Git push to the accessible repository. What limits exploitation: pure read-only access is all that is exposed - no code execution, no write capability; the attacker must already be an authorized contributor to at least one repository in the installation; the target repository must be within the same GitHub App installation boundary, not arbitrary external repositories.

The CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N, score 6.5) accurately reflects the real-world risk profile: exploitation is network-reachable, low-complexity, and requires only push access to one repository in the installation - a meaningful but not trivial prerequisite. Impact is bounded to read-only exposure of private Tekton task YAML; no write access, code execution, or availability impact is involved. The absence of KEV listing and POC code moderates urgency somewhat, but the attack requires no special tooling beyond a crafted PipelineRun annotation and a Git push. The scope is limited to organizations running PAC with multi-repository or org-wide GitHub App installations; single-repository installations are not affected. A key risk amplifier is that private Tekton task definitions may embed secrets, credentials, or sensitive pipeline logic that the repository owner intended to restrict - meaning the confidentiality impact in practice could exceed what a generic C:H label implies. Any team using org-wide GitHub App installations for PAC, even a mid-sized development organization, should treat this as a concrete upgrade priority. No conflicting signals exist between CVSS and the description.

An attacker with push access to a lower-trust repository (e.g., a contractor's project) in an org-wide Pipelines-as-Code GitHub App installation pushes a PipelineRun YAML containing the annotation pipelinesascode.tekton.dev/task pointing to a URL in a private, higher-trust repository within the same installation. When the webhook fires and PAC processes the PipelineRun, it fetches the referenced task YAML using the unscoped installation token and inlines it into the pipeline, exposing the private task's source - potentially including embedded secrets, API keys, or sensitive deployment logic - in PAC's resolution output or pipeline logs. No public proof-of-concept code has been identified at time of analysis.