diff --git a/public/manifest.json b/public/manifest.json
index f0f6b61..5a81350 100644
--- a/public/manifest.json
+++ b/public/manifest.json
@@ -8,7 +8,6 @@
     "storage",
     "unlimitedStorage",
     "cookies",
-    "activeTab",
     "tabs",
     "alarms",
     "offscreen"
diff --git a/src/background/index.ts b/src/background/index.ts
index 255204b..879c9b5 100644
--- a/src/background/index.ts
+++ b/src/background/index.ts
@@ -462,6 +462,14 @@ messageBus.on('SF_UPDATE_RECORD', async (message, sender): Promise<MessageRespon
 });
 
 messageBus.on('SF_API_REQUEST', async (message, sender): Promise<MessageResponse> => {
+  // Security (#68): restrict privileged handler to trusted extension contexts.
+  if (message.source !== 'app' && message.source !== 'popup') {
+    return {
+      success: false,
+      error: { code: 'UNAUTHORIZED_SOURCE', message: `SF_API_REQUEST not allowed from source: ${message.source}` },
+      requestId: message.requestId,
+    };
+  }
   try {
     const { method, path, body, rawText } = message.payload as {
       method: 'GET' | 'POST' | 'PATCH' | 'DELETE' | 'PUT';
@@ -483,6 +491,14 @@ messageBus.on('SF_API_REQUEST', async (message, sender): Promise<MessageResponse
 });
 
 messageBus.on('SF_EXECUTE_ANONYMOUS', async (message, sender): Promise<MessageResponse> => {
+  // Security (#68): restrict privileged handler to trusted extension contexts.
+  if (message.source !== 'app' && message.source !== 'popup') {
+    return {
+      success: false,
+      error: { code: 'UNAUTHORIZED_SOURCE', message: `SF_EXECUTE_ANONYMOUS not allowed from source: ${message.source}` },
+      requestId: message.requestId,
+    };
+  }
   try {
     const { apexBody } = message.payload as { apexBody: string };
     const org = await resolveSfOrg(message.payload, sender);
@@ -902,6 +918,14 @@ messageBus.on('DATA_EXPORT', async (message): Promise<MessageResponse> => {
 });
 
 messageBus.on('DATA_IMPORT', async (message): Promise<MessageResponse> => {
+  // Security (#68): restrict privileged handler to trusted extension contexts.
+  if (message.source !== 'app' && message.source !== 'popup') {
+    return {
+      success: false,
+      error: { code: 'UNAUTHORIZED_SOURCE', message: `DATA_IMPORT not allowed from source: ${message.source}` },
+      requestId: message.requestId,
+    };
+  }
   try {
     const payload = message.payload as Record<string, unknown>;
     const result = await storage.importUserData(payload);
@@ -984,9 +1008,14 @@ messageBus.on('OPEN_FULL_APP', async (message): Promise<MessageResponse> => {
 messageBus.on('ORG_LIST', async (message): Promise<MessageResponse> => {
   const orgs = await storage.getOrgs();
   const activeOrgId = await storage.getActiveOrgId();
+  // Security (#67): strip tokens before sending to UI surfaces.
+  // Tokens never need to leave the background worker.
+  const safeOrgs = Object.values(orgs).map(({ orgId, username, instanceUrl, displayName, environment, nickname, id, connectedAt, lastUsedAt, apiVersion }) => ({
+    orgId, username, instanceUrl, displayName, environment, nickname, id, connectedAt, lastUsedAt, apiVersion,
+  }));
   return {
     success: true,
-    data: { orgs: Object.values(orgs), activeOrgId },
+    data: { orgs: safeOrgs, activeOrgId },
     requestId: message.requestId,
   };
 });
diff --git a/src/services/salesforce/api-client.ts b/src/services/salesforce/api-client.ts
index 9557d76..712db6f 100644
--- a/src/services/salesforce/api-client.ts
+++ b/src/services/salesforce/api-client.ts
@@ -134,11 +134,35 @@ export class SalesforceApiClient {
 
   /** Fetch next page of query results */
   async queryMore<T = Record<string, unknown>>(nextRecordsUrl: string): Promise<QueryResult<T>> {
+    // Security (#65): validate nextRecordsUrl is a relative Salesforce path.
+    if (/^https?:\/\//i.test(nextRecordsUrl)) {
+      const allowedOrigin = new URL(this.config.instanceUrl).origin;
+      const requestedOrigin = new URL(nextRecordsUrl).origin;
+      if (requestedOrigin !== allowedOrigin) {
+        throw new SalesforceApiError(
+          `queryMore blocked: nextRecordsUrl origin (${requestedOrigin}) does not match org instanceUrl (${allowedOrigin})`,
+          403,
+          'URL_ORIGIN_MISMATCH',
+        );
+      }
+    }
     return this.request<QueryResult<T>>(nextRecordsUrl, { useFullPath: true });
   }
 
   /** Fetch next page of Tooling API query results */
   async toolingQueryMore<T = Record<string, unknown>>(nextRecordsUrl: string): Promise<QueryResult<T>> {
+    // Security (#65): validate nextRecordsUrl is a relative Salesforce path.
+    if (/^https?:\/\//i.test(nextRecordsUrl)) {
+      const allowedOrigin = new URL(this.config.instanceUrl).origin;
+      const requestedOrigin = new URL(nextRecordsUrl).origin;
+      if (requestedOrigin !== allowedOrigin) {
+        throw new SalesforceApiError(
+          `toolingQueryMore blocked: nextRecordsUrl origin (${requestedOrigin}) does not match org instanceUrl (${allowedOrigin})`,
+          403,
+          'URL_ORIGIN_MISMATCH',
+        );
+      }
+    }
     return this.request<QueryResult<T>>(nextRecordsUrl, { useFullPath: true });
   }
 
@@ -284,11 +308,25 @@ export class SalesforceApiClient {
     body?: unknown,
     opts: { rawText?: boolean } = {},
   ): Promise<RawCallResult> {
-    const url = /^https?:\/\//.test(path)
-      ? path
-      : path.startsWith('/services/')
-        ? `${this.config.instanceUrl}${path}`
-        : `${this.config.instanceUrl}${API_BASE_PATH}/${this.config.apiVersion}${path.startsWith('/') ? path : `/${path}`}`;
+    let url: string;
+    if (/^https?:\/\//.test(path)) {
+      // Security (#65): reject absolute URLs whose origin does not match the org's instanceUrl.
+      // Prevents Bearer-token exfiltration to attacker-controlled domains.
+      const allowedOrigin = new URL(this.config.instanceUrl).origin;
+      const requestedOrigin = new URL(path).origin;
+      if (requestedOrigin !== allowedOrigin) {
+        throw new SalesforceApiError(
+          `rawCall blocked: absolute URL origin (${requestedOrigin}) does not match org instanceUrl (${allowedOrigin})`,
+          403,
+          'URL_ORIGIN_MISMATCH',
+        );
+      }
+      url = path;
+    } else if (path.startsWith('/services/')) {
+      url = `${this.config.instanceUrl}${path}`;
+    } else {
+      url = `${this.config.instanceUrl}${API_BASE_PATH}/${this.config.apiVersion}${path.startsWith('/') ? path : `/${path}`}`;
+    }
 
     const response = await fetch(url, {
       method,
diff --git a/src/services/salesforce/bulk-api.ts b/src/services/salesforce/bulk-api.ts
index 7d915bc..7253b84 100644
--- a/src/services/salesforce/bulk-api.ts
+++ b/src/services/salesforce/bulk-api.ts
@@ -281,7 +281,11 @@ export class BulkApiService {
       const values = headers.map(h => {
         const val = record[h];
         if (val === null || val === undefined) return '';
-        const str = String(val);
+        let str = String(val);
+        // Security (#66): neutralize formula-injection payloads in upload CSV.
+        if (/^[=+\-@\t\r]/.test(str)) {
+          str = `'${str}`;
+        }
         if (str.includes(',') || str.includes('"') || str.includes('\n')) {
           return `"${str.replace(/"/g, '""')}"`;
         }
diff --git a/src/services/storage/index.ts b/src/services/storage/index.ts
index 31db557..49b4f5b 100644
--- a/src/services/storage/index.ts
+++ b/src/services/storage/index.ts
@@ -55,10 +55,15 @@ export class StorageService {
     return orgs[orgId] ?? null;
   }
 
-  /** Save or update an org */
+  /** Save or update an org (tokens stripped — stored only in session storage) */
   async saveOrg(org: SalesforceOrg): Promise<void> {
     const orgs = await this.getOrgs();
-    orgs[org.orgId] = org;
+    // Security (#64): never persist tokens to local storage.
+    // Tokens live only in chrome.storage.session via setSessionToken().
+    const { accessToken, tokenExpiresAt, ...safeOrg } = org;
+    void accessToken;
+    void tokenExpiresAt;
+    orgs[org.orgId] = safeOrg as SalesforceOrg;
     await this.setLocal(STORAGE_KEYS.ORGS, orgs);
   }
 
diff --git a/src/ui/utils/csv.ts b/src/ui/utils/csv.ts
index 67d7a3d..f2ece31 100644
--- a/src/ui/utils/csv.ts
+++ b/src/ui/utils/csv.ts
@@ -6,9 +6,19 @@
 
 import type { FlatRecord } from './records';
 
+/** Neutralize formula-injection payloads (CSV injection / DDE). */
+function neutralizeFormulaInjection(s: string): string {
+  // Prefix with a single quote if the cell starts with a dangerous character.
+  // Excel/Sheets treats leading = + - @ \t \r as formula/DDE triggers.
+  if (/^[=+\-@\t\r]/.test(s)) {
+    return `'${s}`;
+  }
+  return s;
+}
+
 function escapeCsvValue(value: unknown): string {
   if (value === null || value === undefined) return '';
-  const s = String(value);
+  const s = neutralizeFormulaInjection(String(value));
   if (/[",\n\r]/.test(s)) {
     return `"${s.replace(/"/g, '""')}"`;
   }
diff --git a/src/ui/utils/excel.ts b/src/ui/utils/excel.ts
index 593f89d..46de2ea 100644
--- a/src/ui/utils/excel.ts
+++ b/src/ui/utils/excel.ts
@@ -25,11 +25,16 @@ export async function recordsToExcel(
   sheetName: string = 'Sheet1'
 ): Promise<void> {
   const XLSX = await loadXLSX();
-  // Filter records to only include specified columns
+  // Filter records to only include specified columns and neutralize formula injection (#66)
   const filtered = records.map(record => {
     const filtered: Record<string, unknown> = {};
     for (const col of columns) {
-      filtered[col] = record[col];
+      const val = record[col];
+      if (typeof val === 'string' && /^[=+\-@\t\r]/.test(val)) {
+        filtered[col] = `'${val}`;
+      } else {
+        filtered[col] = val;
+      }
     }
     return filtered;
   });
@@ -83,7 +88,13 @@ export async function recordsToExcelBuffer(
   const filtered = records.map(record => {
     const filtered: Record<string, unknown> = {};
     for (const col of columns) {
-      filtered[col] = record[col];
+      const val = record[col];
+      // Security (#66): neutralize formula-injection payloads in Excel export.
+      if (typeof val === 'string' && /^[=+\-@\t\r]/.test(val)) {
+        filtered[col] = `'${val}`;
+      } else {
+        filtered[col] = val;
+      }
     }
     return filtered;
   });