CVE-2026-27626 — Vulnerability in github.com/OliveTin/OliveTin —...

### Summary OliveTin's shell mode safety check (`checkShellArgumentSafety`) blocks several dangerous argument types but not `password`. A user supplying a `password`-typed argument can inject shell metacharacters that execute arbitrary OS commands. A second independent vector allows unauthenticated RCE via webhook-extracted JSON values that skip type safety checks entirely before reaching `sh -c`. ### Details **Vector 1 — `password` type bypasses shell safety check (PR:L)** `service/internal/executor/arguments.go` has two gaps: ```go // Line 198-199 — TypeSafetyCheck returns nil (no error) for password type case "password": return nil // accepts ANY string including ; | ` $() // Line 313 — checkShellArgumentSafety blocks dangerous types but not password unsafe := map[string]bool{ "url": true, "email": true, "raw_string_multiline": true, "very_dangerous_raw_string": true, // "password" is absent — not blocked } ``` Shell execution at `service/internal/executor/executor_unix.go:18`: ```go exec.CommandContext(ctx, "sh", "-c", finalParsedCommand) ``` A user supplies a `password` argument value of `'; id; echo '` → `sh -c` interprets the shell metacharacters → arbitrary command execution. This is not the "admin already has access" pattern: OliveTin explicitly enforces an admin/user boundary where admins define commands and users only supply argument values. The `password` type is the documented, intended mechanism for user-supplied sensitive values. The safety check exists precisely to prevent users from escaping this boundary — `password` is the one type it fails to block. **Vector 2 — Webhook JSON extraction skips TypeSafetyCheck entirely (PR:N)** `service/internal/executor/handler.go:153-157` extracts arbitrary key-value pairs from webhook JSON payloads and injects them into `ExecutionRequest.Arguments`. These webhook-extracted arguments have no corresponding config-defined `ActionArgument` entry, so `parseActionArguments()` in `arguments.go` finds no type to check against and skips `TypeSafetyCheck` entirely. The values are templated directly into the shell command and passed to `sh -c`. Example: an admin command template `git pull && echo {{ git_message }}` with Shell mode enabled. A webhook POST with `{"git_message": "x; id"}` injects `id` into the shell command. The webhook endpoint is unauthenticated by default (`authType: none` in default config). ### PoC ```bash # Vector 1 — authenticated user with password-type argument curl -X POST http://localhost:1337/api/StartAction \ -H "Content-Type: application/json" \ -d '{"actionId": "run-command", "arguments": [{"name": "pass", "value": "'; id; echo '"}]}' # Vector 2 — unauthenticated webhook curl -X POST http://localhost:1337/webhook/git-deploy \ -H "Content-Type: application/json" \ -d '{"git_message": "x; id #", "git_author": "attacker"}' ``` Confirmed on `jamesread/olivetin:latest` (3000.10.0), 3/3 runs. Both vectors produced `uid=1000(olivetin)` output and arbitrary file write to `/tmp/pwned`. ### Impact - **Vector 1**: Any authenticated user (registration enabled by default, `authType: none` by default) can execute arbitrary OS commands on the OliveTin host with the permissions of the OliveTin process. - **Vector 2**: Unauthenticated attacker can achieve the same if the instance receives webhooks from external sources, which is a primary OliveTin use case. Combined: unauthenticated RCE on any OliveTin instance using Shell mode with webhook-triggered actions.