GitHub Security Advisory: GHSA-cv4x-93xx-wgfj
Package: github.com/tektoncd/pipeline (GO)
Severity: MODERATE (CVSS 6.5)
CWE: CWE-129: Improper Validation of Array Index, CWE-400: Uncontrolled Resource Consumption
Vulnerable versions: >= 1.4.0, < 1.6.1
Patched in: 1.6.1

Summary: Tekton Pipelines controller panic via long resolver name in TaskRun/PipelineRun

Details:
### 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

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](https://github.com/tektoncd/pipeline/commit/5eead3f859b9f938e86039e4d29185092c1d4ee6