Tekton Pipelines controller panic via long resolver name in TaskRun/PipelineRunGHSA-cv4x-93xx-wgfj

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:

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

Fixed in versions 1.0.1, 1.3.3, 1.6.1, 1.9.2, 1.10.2.

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 (main): 5eead3f859b9
• Fix (v1.10.x): 01673237c464
• Fix (v1.9.x): edc64bbf2232
• Fix (v1.6.x): 0fa2d66cff81
• Fix (v1.3.x): 5e4905fb6754
• Fix (v1.0.x): ebc197e2b973
• Introduced in: ea1fa7ad1fdc ("Remote Resolution Refactor")