fix(security): close MEDIUM ASVS findings — JWT pinning, SSE tickets, SSRF, mTLS pin, rate limits + correctness bugs

Auth (V2.1.1/V3.1.2, V2.1.3, V3.1.1):
- Pin JWT iss/aud/typ at mint and require+verify them at decode; revocation
  (jti denylist + tokens_valid_from) still enforced.
- Change-password now requires min_length=12.
- SSE auth moves off JWT-in-URL to a single-use 60s opaque ticket
  (POST /auth/sse-ticket); raw JWT in query no longer authenticates a stream.
  Removed dead fail-open get_stream_user helper.

Egress (V5.1.1, V9.1.1/V14.1.3):
- Webhook delivery + CRUD reject SSRF destinations (private/loopback/link-local/
  metadata, IPv4-mapped, multi-A-record) via resolved-IP validation, pin to the
  vetted IP, and never auto-follow redirects. Opt-out via DECNET_WEBHOOK_ALLOW_PRIVATE.
- UpdaterClient pins the worker leaf cert SHA-256 against the stored per-host
  fingerprint (fail closed on missing/mismatch); DECNET_VERIFY_HOSTNAME now
  defaults True.

Hardening (V13.1.3, V4.1.4, V13.1.2):
- Rate-limit change-password (5/min), enroll-bundle (10/min), webhook-create
  (20/min), host-delete (20/min) via the existing slowapi limiter.
- Correct false 'global auth middleware' comment; document enroll-bundle proxy
  trust.

Correctness (BUG-7..11):
- BUG-7 unbound bus in finally; BUG-8 apply_ceiling clamps to min(base,ceiling);
  BUG-9 commit before emit; BUG-10 multi-actor rearm for sub-threshold identities;
  BUG-11 normalize naive timestamps to UTC.

Already-closed (no change): V14.1.1, V2.1.2/V3.1.3, V5.1.2. Tests added for
every fix; unanimous adversarial review.

decnet/web/router/auth/api_change_pass.py

@@ -2,12 +2,13 @@
 from datetime import datetime, timezone
 from typing import Any, Optional
 
-from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi import APIRouter, Depends, HTTPException, Request, status
 
 from decnet.telemetry import traced as _traced
 from decnet.web.auth import ahash_password, averify_password
 from decnet.web.dependencies import get_current_user_unchecked, invalidate_user_cache, repo
 from decnet.web.db.models import ChangePasswordRequest, MessageResponse
+from decnet.web.limiter import limiter
 
 router = APIRouter()
 
@@ -19,19 +20,21 @@ router = APIRouter()
     responses={
         400: {"description": "Bad Request (e.g. malformed JSON)"},
         401: {"description": "Could not validate credentials"},
-        422: {"description": "Validation error"}
+        422: {"description": "Validation error"},
+        429: {"description": "Too many password-change attempts — retry after the window resets"},
     },
 )
+@limiter.limit("5/minute")
 @_traced("api.change_password")
-async def change_password(request: ChangePasswordRequest, current_user: str = Depends(get_current_user_unchecked)) -> dict[str, str]:
+async def change_password(request: Request, body: ChangePasswordRequest, current_user: str = Depends(get_current_user_unchecked)) -> dict[str, str]:
     _user: Optional[dict[str, Any]] = await repo.get_user_by_uuid(current_user)
-    if not _user or not await averify_password(request.old_password, _user["password_hash"]):
+    if not _user or not await averify_password(body.old_password, _user["password_hash"]):
         raise HTTPException(
             status_code=status.HTTP_401_UNAUTHORIZED,
             detail="Incorrect old password",
         )
 
-    _new_hash: str = await ahash_password(request.new_password)
+    _new_hash: str = await ahash_password(body.new_password)
     await repo.update_user_password(current_user, _new_hash, must_change_password=False)
     # Changing a password revokes every existing session for this user (incl.
     # the current one): the caller's next request 401s and re-authenticates.