Summary

The Tekton Pipelines git resolver is vulnerable to path traversal via the pathInRepo parameter. A tenant with permission to create ResolutionRequests (e.g. by creating TaskRuns or PipelineRuns that use the git resolver) can read arbitrary files from the resolver pod's filesystem, including ServiceAccount tokens. The file contents are returned base64-encoded in resolutionrequest.status.data.

Details

The git resolver's getFileContent() function in pkg/resolution/resolver/git/repository.go constructs a file path by joining the repository clone directory with the user-supplied pathInRepo parameter:

go fileContents, err := os.ReadFile(filepath.Join(repo.directory, path))

The pathInRepo parameter is not validated for path traversal sequences. An attacker can supply values like ../../../../etc/passwd to escape the cloned repository directory and read arbitrary files from the resolver pod's filesystem.

The vulnerability was introduced in commit 318006c4e3a5 which switched the git resolver from the go-git library (using an in-memory filesystem that cannot be escaped) to shelling out to the git binary and reading files with os.ReadFile() from the real filesystem.

Impact

Arbitrary file read — A namespace-scoped tenant who can create TaskRuns or PipelineRuns with git resolver parameters can read any file readable by the resolver pod process.

Credential exfiltration and privilege escalation — The resolver pod's ServiceAccount token is readable at a well-known path (/var/run/secrets/kubernetes.io/serviceaccount/token). In the default RBAC configuration, the tekton-pipelines-resolvers ServiceAccount has get, list, and watch permissions on secrets cluster-wide. An attacker who exfiltrates this token gains the ability to read all Secrets across all namespaces, escalating from namespace-scoped access to cluster-wide secret access.

Patches

Fixed in 1.0.x, 1.3.x, 1.6.x, 1.9.x, 1.10.x.

The fix validates pathInRepo to reject paths containing .. components at parameter validation time, and adds a containment check using filepath.EvalSymlinks() to prevent symlink-based escapes from attacker-controlled repositories.

Workarounds

There is no workaround other than restricting which users can create TaskRuns, PipelineRuns, or ResolutionRequests that use the git resolver. Administrators can also reduce the impact by scoping the resolver pod's ServiceAccount RBAC permissions using a custom ClusterRole with more restrictive rules.

Affected Versions

All releases from v1.0.0 through v1.10.0, including all patch releases:

- v1.0.0, v1.1.0, v1.2.0 - v1.3.0, v1.3.1, v1.3.2 - v1.4.0, v1.5.0, v1.6.0, v1.7.0 - v1.9.0, v1.9.1, v1.10.0

Releases prior to v1.0.0 (e.g. v0.70.0 and earlier) are not affected because they used the go-git library's in-memory filesystem where path traversal cannot escape the git worktree.

Acknowledgments

This vulnerability was reported by Oleh Konko (@1seal), who provided a thorough vulnerability analysis, proof-of-concept, and review of the fix. Thank you!

References

- Fix: (link to merged PR/commit) - Introduced in: 318006c4e3a5 ("fix: resolve Git Anonymous Resolver excessive memory usage")

Summary

A user with permission to create or update a TaskRun or PipelineRun can crash the Tekton Pipelines controller by setting .spec.taskRef.resolver (or .spec.pipelineRef.resolver) to a string of 31 characters or more, causing a denial of service for all reconciliation.

Details

The controller panics in GenerateDeterministicNameFromSpec when building a deterministic ResolutionRequest name. The generated name has the format {resolver}-{hash} and, when the resolver name is long enough, the result exceeds the DNS-1123 label limit of 63 characters.

The truncation logic attempts to find a word boundary using strings.LastIndex(name, " "). Since the generated name never contains spaces (it is composed of the resolver name, a dash, and a hex-encoded hash), LastIndex returns -1, which is then used as a slice bound:

go return name[:strings.LastIndex(name[:maxLength], " ")], nil // strings.LastIndex returns -1 → panic: slice bounds out of range [:-1]

The panic crashes the controller. Because the offending TaskRun or PipelineRun is re-reconciled on restart, the controller enters a CrashLoopBackOff, blocking all TaskRun and PipelineRun reconciliation cluster-wide until the offending resource is manually deleted.

Built-in resolvers use short names (git, cluster, bundles, hub) and are not affected under normal usage. The vulnerability is exploitable by any user who can create TaskRuns or PipelineRuns with a custom resolver name.

Impact

Denial of service — A single malicious TaskRun or PipelineRun with a long resolver name is sufficient to crash the Tekton Pipelines controller into a restart loop, blocking all CI/CD reconciliation cluster-wide until the resource is removed.

Patches

(to be filled in: e.g. "Fixed in versions 1.10.1, 1.9.1, ...")

The fix computes the hash first, then truncates only the prefix (resolver name) to fit within the DNS-1123 label limit, preserving the full hash to maintain determinism and uniqueness of ResolutionRequest names.

Workarounds

Restrict who can create TaskRun and PipelineRun resources via Kubernetes RBAC. There is no validation-side workaround without patching.

Affected Versions

All releases from v0.60.0 through v1.10.0.

The vulnerable truncation logic was introduced in commit ea1fa7ad1fdc ("Remote Resolution Refactor"), first released in v0.60.0 (2024-05-22).

Currently supported affected releases: - v1.10.x (latest) - v1.9.x (LTS, EOL 2027-01-30) - v1.6.x (LTS, EOL 2026-10-31) - v1.3.x (LTS, EOL 2026-08-04) - v1.0.x (LTS, EOL 2026-04-29)

Releases prior to v0.60.0 are not affected — the truncation code did not exist.

Acknowledgments

This vulnerability was reported by Oleh Konko (@1seal), who provided a thorough vulnerability analysis, proof-of-concept, and review of the fix. Thank you!

References

- Fix: (link to merged PR/commit) - Introduced in: ea1fa7ad1fdc ("Remote Resolution Refactor")