CVE-2026-31817 — Vulnerability in github.com/OliveTin/OliveTin —...

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: ```go 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: ```go _, 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: ```go 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: ```go // 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): ```json { "bindingId": "<any-executable-action-id>", "uniqueTrackingId": "../../../tmp/pwned" } ``` Assuming the action title is `Ping the Internet` and the timestamp is `1741320000`, the constructed filename becomes: ``` Ping the Internet.1741320000.../../../tmp/pwned ``` When `path.Join` processes this with a configured results directory like `/var/olivetin/logs`: ``` path.Join("/var/olivetin/logs", "Ping the Internet.1741320000.../../../tmp/pwned.yaml") ``` `path.Clean` resolves the traversal: 1. Path segments: `["var", "olivetin", "logs", "Ping the Internet.1741320000...", "..", "..", "..", "tmp", "pwned.yaml"]` 2. The `..` segments traverse upward past the log directory. 3. Final resolved path: `/tmp/pwned.yaml` Two files are written: - **`.yaml` file** — contains YAML-serialized `InternalLogEntry` (action title, icon, timestamps, exit code, output, tags, username, tracking ID) - **`.log` file** — contains the raw command output (potentially attacker-influenced if the action echoes its arguments) ### Impact - **Arbitrary file write** to any path writable by the OliveTin process. - OliveTin frequently runs as root inside Docker containers, so the writable scope is often the entire filesystem. - An attacker could: - Overwrite OliveTin's own `sessions.yaml` to inject authenticated sessions. - Write to entity file directories to inject malicious entity data. - Write to system cron directories or other locations to achieve remote code execution. - Cause denial of service by overwriting critical system files. ### Suggested Fix Validate the `UniqueTrackingId` to ensure it only contains safe characters before use. A strict UUID format check is the simplest approach: ```go import "regexp" var validTrackingID = regexp.MustCompile(`^[a-fA-F0-9\-]+$`) // In ExecRequest, before accepting the user-supplied ID: if req.TrackingID == "" || !validTrackingID.MatchString(req.TrackingID) { req.TrackingID = uuid.NewString() } ``` Alternatively, sanitize the filename in `stepSaveLog` by stripping or rejecting path separators and `..` sequences.