OliveTin's unsafe parsing of UniqueTrackingId can be used to write files

When the saveLogs feature is enabled, OliveTin persists execution log entries to disk. The filename used for these log files is constructed in part from the user-supplied UniqueTrackingId field in the StartAction API request. This value is not validated or sanitized before being used in a file path, allowing an attacker to use directory traversal sequences (e.g., ../../../) to write files to arbitrary locations on the filesystem.

Affected Code

Entry point — service/internal/api/api.go (line 130):

The UniqueTrackingId from the API request is passed directly to the executor without validation:

execReq := executor.ExecutionRequest{
    Binding:    pair,
    TrackingID: req.Msg.UniqueTrackingId, // user-controlled, no validation
    // ...
}

Tracking ID accepted as-is — service/internal/executor/executor.go (lines 508–512):

The tracking ID is only replaced with a UUID if it is empty or a duplicate. Any other string, including one containing path separators, is accepted:

_, isDuplicate := e.GetLog(req.TrackingID)

if isDuplicate || req.TrackingID == "" {
    req.TrackingID = uuid.NewString()
}

Filename construction — service/internal/executor/executor.go (line 1042):

The tracking ID is interpolated directly into the log filename:

filename := fmt.Sprintf("%v.%v.%v",
    req.logEntry.ActionTitle,
    req.logEntry.DatetimeStarted.Unix(),
    req.logEntry.ExecutionTrackingID,
)

File write — service/internal/executor/executor.go (lines 1068–1069 and 1082–1083):

The filename is joined to the configured log directory using path.Join, which calls path.Clean internally. path.Clean resolves .. path segments, causing the final file path to escape the intended directory:

// Results file (.yaml)
filepath := path.Join(dir, filename+".yaml")
err = os.WriteFile(filepath, data, 0600)

// Output file (.log)
filepath := path.Join(dir, filename+".log")
err := os.WriteFile(filepath, []byte(data), 0600)

Proof of Concept

An attacker sends the following StartAction request (Connect RPC or REST):

{
  "bindingId": "<any-executable-action-id>",
  "uniqueTrackingId": "../../../tmp/pwned"
}