# SESSION-0026.4 — OHM security-audit subsession (newest endpoints, rate-limiting/abuse, frontend posture)

- **Role:** subsession 0026.4 of OHM security-audit driver session 0026.
- **Parent transcript:** SESSION-0026.0-TRANSCRIPT-2026-05-28T13-46--INPROGRESS.md
- **Mode:** READ-ONLY. No mutations. No secret bytes printed.
- **Target:** rfc-app @ /Users/benstull/git/rfc-app, tag v0.24.0 (HEAD 28015ed).
- **Window:** 2026-05-28T13-46 → 13-50 (America/Los_Angeles).

## Surface assigned
Newest endpoints from session 0022 work (proposed_use_cases writes #26,
PUT /api/me/last-state #29, Claude Haiku tag suggestions #27); rate
limiting / abuse on OTC + beta-request + suggest-tags + propose; frontend
token/secret handling, VITE_ public-vs-secret discipline, token storage,
CSP/security headers, npm audit.

## Pre-state
Fresh read-only checkout at v0.24.0. No prior findings in this subsession.

## Turn-by-turn arc

1. Enumerated backend/app + frontend/src layout, confirmed v0.24.0 tag.
2. Read tag_suggest.py in full, useLastState.js, main.py (full).
   - tag_suggest: output strictly constrained to the corpus tag universe
     (parse_reply maps replies back to canonical spellings, drops invented
     tags). Prompt-injection into the Haiku call can't escape the tag set;
     worst case is a junk/empty suggestion list. Per-user in-process rate
     limit (TAG_SUGGEST_RATE_MAX default 30/60s) + require_contributor gate
     + draft truncation (title 300, pitch/use_case 4000) + universe cap 200
     bound the LLM cost surface. SOLID.
3. Located + read the #26 use_case writes (api.py propose, api_prs.py
   open-pr), the #29 last-state route, the suggest-tags route.
   - last-state: keyed on user.user_id from the session in BOTH read
     (/api/auth/me) and write (PUT /api/me/last-state). No user-supplied
     id anywhere → no cross-user read/write (IDOR). require_user gate.
     resume_enabled opt-out respected. route bounded 2048, state is a
     dict serialized as JSON. SOLID on authz.
4. Checked propose + open-pr authz: both require_contributor (granted,
   non-muted, authenticated). use_case bounded max_length=8000. SOLID.
5. Frontend rendering of proposed_use_case: grep found
   ProposalView.jsx:172 renders it via marked.parse() into
   dangerouslySetInnerHTML. No DOMPurify anywhere in the project
   (confirmed by grep across frontend/src + package.json).
6. KILLED a refutation attempt: verified marked default does NOT sanitize.
   Ran node one-liner: marked.parse('<img src=x onerror=alert(1)>') emits
   the raw <img onerror> tag, and [a](javascript:alert(2)) emits a live
   javascript: href. So this is a real stored-XSS sink, not theoretical.
7. Confirmed the XSS audience: GET /api/proposals/{pr_number} is
   ANONYMOUS-readable (no require_ gate; uses current_user only for
   affordances). Admins reviewing a proposal (who hold merge/decline)
   render the payload → privileged-victim XSS.
8. Frontend token storage: grep for localStorage/sessionStorage/
   document.cookie/Authorization/Bearer in api.js → ZERO hits. Auth is
   server cookie-session (credentials:'include'); device-trust + session
   cookies are HttpOnly+Secure+SameSite=Lax (main.py). No token in JS
   reach → XSS can't exfil an auth token directly. SOLID.
9. VITE_ discipline: all VITE_ vars are genuinely public — APP_NAME,
   BETA_CONTACT, TURNSTILE_SITE_KEY (public by design), AMPLITUDE_API_KEY
   (Amplitude browser ingestion key, public by design; .env.example
   explicitly documents it as `flotilla overlay set`, NOT secret), policy
   URLs. No secret shipped as a VITE_ var. SOLID.
10. npm audit (frontend): 0 vulnerabilities (info/low/moderate/high/
    critical all 0). SOLID.
11. OTC abuse: request_code has a per-email cooldown
    (OTC_REQUEST_COOLDOWN_SECONDS default 60) AND the route runs
    turnstile.verify_token BEFORE request_code (so a failed challenge
    spends no budget / sends no mail). Email-bomb + LLM-cost surfaces
    mitigated. Cooldown is per-email not per-IP, but Turnstile covers the
    bot/IP dimension. SOLID with one caveat (below).
12. beta-request: require_user gated (not anon), admin notification fires
    once via the was_already_complete guard. Not anon-abusable.
13. Security headers: app has only SessionMiddleware — no CSP / X-Frame /
    X-Content-Type / HSTS. nginx conf (deploy/nginx/ohm.wiggleverse.org.conf)
    sets only Cache-Control — NO security headers either. So nothing
    backstops the XSS sinks at the header layer.

## Cut state — findings

### F1 — Stored XSS via proposed_use_case rendered through marked + dangerouslySetInnerHTML (no sanitizer)
- **Location:** frontend/src/components/ProposalView.jsx:172 (sink);
  source written at backend/app/api.py:841-854 (#26 propose) and
  backend/app/api_prs.py:186-199 (#26 open-pr); served unsanitized via
  GET /api/proposals/{pr_number} (api.py:716, anon-readable);
  proposed_use_case max_length=8000.
- **Issue:** marked does not sanitize by default (verified live: raw
  `<img onerror>` and `javascript:` hrefs pass through), and the project
  has NO DOMPurify. A granted contributor's use_case text renders as
  live HTML in any viewer's browser, including admins who hold
  merge/decline on that proposal.
- **Exploit:** contributor proposes an RFC with
  `<img src=x onerror=...>` in the use case; an admin opens the proposal
  to review it; script runs in the admin's authenticated session
  (CSRF-style writes via the admin's cookie, UI defacement). Auth-token
  exfil is blocked (HttpOnly cookies), but cookie-authenticated state-
  changing requests from the victim's browser are not.
- **Remediation:** sanitize all marked output with DOMPurify before
  dangerouslySetInnerHTML (or configure a safe renderer), at minimum on
  the new proposed_use_case sink. Same pattern should cover the
  pre-existing entry-body sink (F2).
- **Severity:** High. **Confidence:** High (live-verified marked
  passthrough; confirmed no sanitizer; confirmed privileged victim).

### F2 — Pre-existing same-sink XSS on entry body (in-scope by adjacency)
- **Location:** ProposalView.jsx:164 (also Editor.jsx:125 preview path);
  marked.parse(data.entry?.body) → dangerouslySetInnerHTML.
- **Issue:** identical unsanitized sink; the proposed entry body is
  proposer-controlled markdown. Predates v0.24.0 but shares the root
  cause and remediation with F1.
- **Severity:** High. **Confidence:** High. (Flagged as the root-cause
  class so a fix covers both, not just the #26 field.)

### F3 — No security headers at app or nginx layer (defense-in-depth gap)
- **Location:** backend/app/main.py (only SessionMiddleware);
  deploy/nginx/ohm.wiggleverse.org.conf (only Cache-Control).
- **Issue:** no Content-Security-Policy, X-Frame-Options/frame-ancestors,
  X-Content-Type-Options, or HSTS. A CSP would meaningfully blunt F1/F2
  (block inline/onerror script execution). Absence means the XSS sinks
  have no header-layer backstop, and the app is clickjackable.
- **Remediation:** add CSP (script-src self, no unsafe-inline),
  X-Frame-Options DENY / frame-ancestors none, X-Content-Type-Options
  nosniff, HSTS — at the nginx layer is simplest.
- **Severity:** Medium. **Confidence:** High.

### F4 (minor / needs-verification) — OTC cooldown is per-email, not per-IP
- **Location:** backend/app/otc.py:152-164.
- **Issue:** the cooldown keys on email, so one attacker can rotate
  through many target emails (mail-bomb across recipients) without
  tripping a single email's cooldown. Mitigated by the mandatory
  Turnstile gate on /auth/otc/request (main.py:255) when TURNSTILE is
  wired; if TURNSTILE_REQUIRED=false and no secret is set (the default
  dev posture), the gate opens and only the per-email cooldown remains.
- **Remediation:** keep Turnstile required in production; consider an
  IP-scoped request ceiling as belt-and-suspenders.
- **Severity:** Low (prod-config-dependent). **Confidence:** Medium —
  hinges on the deployment's TURNSTILE_REQUIRED + secret state, which
  this subsession did not inspect (operator/§13 record, not code).

## What's solid
- last-state #29: no IDOR (server-session user_id only), no open-redirect
  (resume only navigates client-side react-router routes from "/", with a
  NON_RESUMABLE_PREFIXES skip list; no external URL navigation), state
  blob is bounded + JSON-parsed defensively. Resume redirect is
  one-shot. SOLID.
- tag_suggest #27: prompt-injection contained (output constrained to
  canonical tag universe), cost bounded (per-user rate limit + input
  truncation + universe cap + require_contributor gate), degrades to
  silence on any failure. SOLID.
- Frontend secrets: no auth token in JS-reachable storage; cookies are
  HttpOnly+Secure+SameSite=Lax; no secret shipped as a VITE_ var
  (AMPLITUDE/TURNSTILE keys are public by design). SOLID.
- npm audit: 0 advisories. SOLID.
- OTC/beta-request authz + cost: Turnstile-gated OTC with per-email
  cooldown; beta-request require_user + once-only admin notify. SOLID
  (modulo F4 caveat).

## Driver-needs-to-know
- F1 is the headline: a real, live-verified stored XSS in the #26
  use-case field that can land on an admin reviewer. F2 is the same sink
  on the entry body — fix the sanitizer once, cover both. F3 (no CSP)
  removes the only header-layer backstop. Recommend a single remediation
  wave: add DOMPurify around every marked→dangerouslySetInnerHTML sink +
  add a CSP at nginx.
- F4 depends on the OHM deployment's TURNSTILE_REQUIRED + secret state
  (a §13 record / operator question, not in this code), so verify that
  before downgrading or upgrading it.

## §19.2 candidates (flotilla-core / cross-cutting)
- A shared "render-trusted-markdown" frontend helper (marked + DOMPurify
  in one place) so no future sink reintroduces F1. Not flotilla-core
  (it's rfc-app frontend), but a cross-cutting rfc-app refactor worth a
  roadmap item.
- A security-headers block as a reusable nginx snippet shipped with the
  deploy/ templates — could become a flotilla overlay default.