Tekton Pipelines: Git Resolver Unsanitized Revision Parameter Enables git Argument Injection Leading to RCE

Tekton Pipelines project provides k8s-style resources for declaring CI/CD-style pipelines. Starting in version 1.0.0 and prior to versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1, the git resolver's revision parameter is passed directly as a positional argument to git fetch without any validation that it does not begin with a - character. Because git parses flags from mixed positional arguments, an attacker can inject arbitrary git fetch flags such as --upload-pack=<binary>. Combined with the validateRepoURL function explicitly permitting URLs that begin with / (local filesystem paths), a tenant who can submit ResolutionRequest objects can chain these two behaviors to execute an arbitrary binary on the resolver pod. The tekton-pipelines-resolvers ServiceAccount holds cluster-wide get/list/watch on all Secrets, so code execution on the resolver pod enables full cluster-wide secret exfiltration. Versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1 fix the issue.

The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.