convex-security-audit

Convex security audit

Produces a written findings report covering every public function, every table, and every entry point (HTTP routes, file storage, scheduler). The one rule: every exported query, mutation, and action is a public endpoint anyone on the internet can call with any arguments, so each one must prove who the caller is and what they may touch.

For a ten minute pass, use convex-security-check instead. This skill is the slow, complete version.

When to reach for this

• Before a production launch or a major release
• After an incident, a leaked key, or suspicious data access
• When the codebase has grown past a handful of public functions and nobody has mapped who can call what
• When adding multi tenant, admin, or billing features
• When the user asks for "a full audit", "security review", or "check the whole backend"

Reference files

• references/authorization-patterns.md: open when fixing findings, it has the getCurrentUser helper, customQuery and customMutation wrappers for authed, admin, and tenant scoped access, ownership checks through indexes, and role checks.
• references/attack-surface.md: open during steps 4 through 7, it covers HTTP actions, storage URL leakage, scheduler trust, rate limiting with @convex-dev/rate-limiter, secrets in env, and client supplied IDs.
• references/audit-report-template.md: open at step 8, it is the findings template and the per table data access matrix to fill in.

Audit procedure

Work through the steps in order. Record every finding as you go. Do not fix anything until the inventory is complete; fixing early hides the shape of the problem.

1. Inventory public functions

List every exported query, mutation, and action. These are the attack surface.

rg -n "export const \w+ = (query|mutation|action)\(" convex --glob '!**/_generated/**'

For each one write down: file, name, type, whether a client needs to call it, and whether it is costly (sends email, calls an LLM, creates records) and so needs a rate limit. Anything only called by other Convex functions, crons, or the scheduler should be internalQuery, internalMutation, or internalAction. Flag each of those as a finding.

2. Map auth per function

For every public function from step 1, answer: does it call ctx.auth.getUserIdentity() (or a helper that does) before reading or writing? Which functions are intentionally anonymous?

rg -l "= (query|mutation|action)\(" convex --glob '!**/_generated/**' \
  | xargs rg -L "getUserIdentity|getCurrentUser|authedQuery|authedMutation"

Files that print here contain public functions with no auth call anywhere in the file. Read each one. Anonymous is fine for a public blog list. It is a critical finding for anything that returns or writes user data.

Check that auth helpers throw or return early on a missing identity, and that role checks read the role from your users table, not from client arguments.

3. Map data access per table

For every table in convex/schema.ts, list which public functions read it, which write it, and what condition scopes the access (owner ID, org membership, role, public flag). Fill in the data access matrix from the report template.

Look for:

• Reads with no scoping: ctx.db.query("table").collect() inside a public function
• ctx.db.get(args.someId) followed by a return or patch with no ownership comparison
• Ownership compared against a spoofable value (email, display name) instead of user._id
• .filter() used for scoping instead of .withIndex(); this usually means the scoping was an afterthought
• Return validators that leak fields: v.any(), or spreading a full document that carries passwordHash, stripeCustomerId, or internal flags

rg -n "v\.any\(\)" convex --glob '!**/_generated/**'
rg -n "ctx\.db\.(get|patch|delete|replace)\(args\." convex --glob '!**/_generated/**'

4. Review http.ts

Every route in convex/http.ts is reachable without a Convex client. For each route check: how is the caller verified (webhook signature, bearer token, ctx.auth.getUserIdentity()), is the body validated before use, and does it call only internal.* functions with data it has already verified?

rg -n "http\.route|httpAction\(" convex/http.ts

Webhook handlers that skip signature verification are critical. Routes that call api.* functions from inside an httpAction may be bypassing auth those functions assume they have.

5. Review file storage

Find where upload URLs are generated and where file URLs are returned.

rg -n "storage\.(generateUploadUrl|getUrl|delete)" convex --glob '!**/_generated/**'

generateUploadUrl in a public mutation with no auth lets anyone fill your storage. A query that returns ctx.storage.getUrl(args.fileId) for any ID the client passes is a data leak; the URL works for anyone who holds it.

6. Review scheduled and internal boundaries

Internal functions skip auth by design. The question is whether anything schedules them with unverified input.

rg -n "(runAfter|runAt|runMutation|runAction|interval|cron)\([^)]*\bapi\." convex --glob '!**/_generated/**'

Scheduling an api.* function is a finding: use internal.*. Then trace each internal.* call site back to the public function or route that triggered it and confirm the caller validated ownership before scheduling.

7. Review env and secrets

rg -n -i "(sk_live|sk_test|whsec_|AKIA[0-9A-Z]{16}|-----BEGIN|api[_-]?key\s*[:=]\s*['\"][A-Za-z0-9])" convex src --glob '!**/_generated/**'
rg -n "process\.env\." convex src --glob '!**/_generated/**'

Secrets belong in Convex environment variables (npx convex env set NAME value), read through process.env in the action or HTTP action that makes the external call. A secret literal in source is critical. Anything read from process.env in client code (src/) is public; only non secret VITE_ or NEXT_PUBLIC_ values belong there. Confirm dev and prod deployments use different keys.

8. Write the report

Fill in references/audit-report-template.md. One finding per issue, ordered by severity, each with location, evidence, and a concrete fix. Include the data access matrix. Finish with the list of public functions reviewed and judged correctly anonymous, so the next auditor does not repeat that work.

Severity scale

Severity	Meaning	Examples
Critical	Any anonymous caller can read or change other users' data, or a secret is exposed	Public mutation patches a document by client supplied ID with no ownership check; API key in source; webhook with no signature check
High	An authenticated user can reach data or actions outside their scope	Missing org membership check in a multi tenant query; admin function reads role from client args
Medium	Defense in depth gap with no direct exploit today	Public function that should be internal; no rate limit on a costly action; upload URL with no auth
Low	Hygiene	v.any() on a non sensitive arg; missing return validator; .filter() where an index exists

Example finding

Severity: Critical
Location: convex/tasks.ts, updateTask (mutation, public)
Evidence: handler calls ctx.db.patch(args.taskId, { title: args.title }) after
  requireAuth(ctx) but never compares task.userId to the caller. Any signed in
  user can rename any task by guessing or capturing an ID.
Fix: load the task, compare task.userId to user._id, throw on mismatch. See
  references/authorization-patterns.md, "Ownership checks".
Verified: reproduced by calling updateTask with another user's task ID from the
  dashboard function runner.

Common mistakes

Mistake	Why it breaks	Do this instead
Treating internalMutation as safe without tracing callers	The public function that schedules it may pass unverified IDs	Audit the scheduling call site, not just the internal function
Checking auth only in the UI	Anyone can call the function from the dashboard or a script	Every public handler checks identity itself
Comparing ownership to identity.email	Emails can be reused or unverified across providers	Compare to user._id looked up via tokenIdentifier
Mixing return null and throw for the same case	Leaks record existence through response differences	In queries, return null for both "not found" and "not yours"
Rate limiting only in the client	Attackers skip the client	Use @convex-dev/rate-limiter inside the mutation or action
Signing off after fixes without re running the greps	Fixes often move the problem	Re run steps 1 through 7 after remediation

Checklist

• [ ] Every exported query, mutation, action is listed with its intended caller
• [ ] Every function that should be internal is internal*
• [ ] Every public function either checks identity or is documented as intentionally anonymous
• [ ] Every table has a filled row in the data access matrix
• [ ] Every http.ts route verifies its caller and validates its body
• [ ] Upload URL generation and file URL reads are gated by ownership
• [ ] No api.* reference inside scheduler, cron, or ctx.run* calls
• [ ] No secret literals in source; dev and prod use different keys
• [ ] Costly or abusable mutations and actions are rate limited
• [ ] Report written with severity, location, evidence, and fix for each finding

Docs

• https://docs.convex.dev/llms.txt
• https://docs.convex.dev/auth/functions-auth
• https://docs.convex.dev/functions/internal-functions
• https://docs.convex.dev/functions/http-actions
• https://docs.convex.dev/production/environment-variables