fix(events): drop non-canonical keys from the event update before any check runs (#1346)

PUT /admin/events/:id spreads the body into the UPDATE. SQLite resolves
quoted identifiers case-insensitively, so `{ "Event_Name": ... }` lands
on event_name there — while every check in the handler (validators, the
field-level permission guards, the deny-set) keys on the exact lowercase
name. The deny-set already case-folded for its own columns; every other
column was reachable through a spelling variant.

Every events column and every input-only key the handler accepts is
lowercase snake_case, so a key with any uppercase in it is not something
a legitimate client sends. Such keys are now removed before anything
looks at the body. Postgres was unaffected (quoted identifiers are
case-sensitive there; a variant produced a 500 instead).

Surfaced by the Codex review of the folder-watcher change, where a
photos.upload guard on external_watch could be walked around this way.

Co-authored-by: Paul Nothaft <[email protected]>

backend/__tests__/routes/authzPermissionGaps.test.js

@@ -137,11 +137,17 @@ describe('authorization / ownership gaps', () => {
         // Case-variant keys — SQLite matches columns case-insensitively.
         Password_Hash: 'case-hijack-hash',
         Created_By: 88888,
+        // A case variant of an ORDINARY column must not reach the UPDATE
+        // either: field-level guards in the handler key on the exact name,
+        // and on SQLite the variant would still land on the real column.
+        Event_Name: 'case-variant-name',
+        Welcome_Message: 'case-variant-welcome',
       });
       expect(res.status).toBe(200);
 
       const row = await db('events').where({ id: eventId }).first();
-      expect(row.event_name).toBe('After');        // legit field applied
+      expect(row.event_name).toBe('After');        // legit field applied; Event_Name variant dropped
+      expect(row.welcome_message).toBeFalsy();      // case variant of an ordinary column dropped
       expect(row.created_by).toBe(superId);         // ownership untouched (+ case-variant)
       expect(row.slug).toBe('authz-mass-assign');   // routing identity untouched
       expect(row.share_token).toBe(seedShareToken); // secret untouched

backend/src/routes/adminEvents/crud.js

@@ -1730,10 +1730,18 @@ module.exports = (router) => {
         // Legacy mirrors — rejected explicitly below in favour of customer_*.
         'host_name', 'host_email',
       ];
-      // Case-insensitive match: SQLite treats quoted identifiers
+      // Only canonical keys reach the UPDATE. SQLite resolves quoted
-      // case-insensitively, so a `{ "Password_Hash": ... }` key would
+      // identifiers case-insensitively, so `{ "Event_Name": ... }` lands on
-      // otherwise survive a case-sensitive delete and still hit the real
+      // event_name there while every check in this handler — validators,
-      // column (codex review).
+      // the permission guards on individual fields, the deny-set below — is
+      // keyed on the exact lowercase name. Every events column and every
+      // input-only key this handler accepts is lowercase snake_case, so a key
+      // with any uppercase in it is not something a legitimate client sends;
+      // it is dropped before anything looks at it. The deny-set keeps its own
+      // case-folding as belt and braces (GHSA-3rqx).
+      for (const key of Object.keys(updates)) {
+        if (key !== key.toLowerCase()) delete updates[key];
+      }
       const denied = new Set(IMMUTABLE_EVENT_COLUMNS.map((c) => c.toLowerCase()));
       for (const key of Object.keys(updates)) {
         if (denied.has(key.toLowerCase())) delete updates[key];