diff --git a/apps/mesh/src/api/app.ts b/apps/mesh/src/api/app.ts
index d879b28894..b0c91868ed 100644
--- a/apps/mesh/src/api/app.ts
+++ b/apps/mesh/src/api/app.ts
@@ -1342,18 +1342,28 @@ export async function createApp(options: CreateAppOptions = {}) {
 
   // Public Events endpoint
   app.post("/org/:organizationId/events/:type", async (c) => {
+    const meshContext = c.var.meshContext;
+
+    // Require authentication (user session or API key)
+    const userId = meshContext.auth.user?.id ?? meshContext.auth.apiKey?.userId;
+    if (!userId) {
+      return c.json({ error: "Unauthorized" }, 401);
+    }
+
     const orgId = c.req.param("organizationId");
-    await c.var.meshContext.eventBus.publish(
-      orgId,
-      WellKnownOrgMCPId.SELF(orgId),
-      {
-        data: await c.req.json(),
-        type: `public:${c.req.param("type")}`,
-        subject: c.req.query("subject"),
-        deliverAt: c.req.query("deliverAt"),
-        cron: c.req.query("cron"),
-      },
-    );
+
+    // Verify the authenticated user belongs to the target organization
+    if (orgId !== meshContext.organization?.id) {
+      return c.json({ error: "Forbidden access to organization" }, 403);
+    }
+
+    await meshContext.eventBus.publish(orgId, WellKnownOrgMCPId.SELF(orgId), {
+      data: await c.req.json(),
+      type: `public:${c.req.param("type")}`,
+      subject: c.req.query("subject"),
+      deliverAt: c.req.query("deliverAt"),
+      cron: c.req.query("cron"),
+    });
     return c.json({ success: true });
   });
 
diff --git a/apps/mesh/src/api/routes/public-events.test.ts b/apps/mesh/src/api/routes/public-events.test.ts
new file mode 100644
index 0000000000..28e48c5ba3
--- /dev/null
+++ b/apps/mesh/src/api/routes/public-events.test.ts
@@ -0,0 +1,152 @@
+import { describe, it, expect, mock } from "bun:test";
+import { Hono } from "hono";
+import type { MeshContext } from "../../core/mesh-context";
+import { WellKnownOrgMCPId } from "@decocms/mesh-sdk";
+
+/**
+ * Tests for POST /org/:organizationId/events/:type
+ *
+ * The handler is inline in app.ts, so we replicate it here to verify the
+ * auth + org-ownership guards in isolation.
+ */
+
+type Env = { Variables: { meshContext: MeshContext } };
+
+function createApp(ctx: unknown) {
+  const app = new Hono<Env>();
+  app.use("*", async (c, next) => {
+    c.set("meshContext", ctx as MeshContext);
+    await next();
+  });
+  app.post("/org/:organizationId/events/:type", async (c) => {
+    const meshContext = c.var.meshContext;
+
+    const userId = meshContext.auth.user?.id ?? meshContext.auth.apiKey?.userId;
+    if (!userId) {
+      return c.json({ error: "Unauthorized" }, 401);
+    }
+
+    const orgId = c.req.param("organizationId");
+
+    if (orgId !== meshContext.organization?.id) {
+      return c.json({ error: "Forbidden access to organization" }, 403);
+    }
+
+    await meshContext.eventBus.publish(orgId, WellKnownOrgMCPId.SELF(orgId), {
+      data: await c.req.json(),
+      type: `public:${c.req.param("type")}`,
+      subject: c.req.query("subject"),
+      deliverAt: c.req.query("deliverAt"),
+      cron: c.req.query("cron"),
+    });
+    return c.json({ success: true });
+  });
+  return app;
+}
+
+function postEvent(
+  app: Hono<Env>,
+  orgId: string,
+  type: string,
+  body: unknown,
+  query?: string,
+) {
+  const qs = query ? `?${query}` : "";
+  return app.request(`/org/${orgId}/events/${type}${qs}`, {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify(body),
+  });
+}
+
+describe("POST /org/:organizationId/events/:type", () => {
+  it("rejects unauthenticated requests with 401", async () => {
+    const app = createApp({
+      auth: { user: undefined, apiKey: undefined },
+      organization: undefined,
+      eventBus: { publish: mock() },
+    });
+
+    const res = await postEvent(app, "org_victim", "data", {
+      payload: "attack",
+    });
+
+    expect(res.status).toBe(401);
+    const body = (await res.json()) as { error: string };
+    expect(body.error).toBe("Unauthorized");
+  });
+
+  it("rejects cross-tenant access with 403", async () => {
+    const publishMock = mock();
+    const app = createApp({
+      auth: { user: { id: "user_1" } },
+      organization: { id: "org_attacker" },
+      eventBus: { publish: publishMock },
+    });
+
+    const res = await postEvent(app, "org_victim", "data", {
+      payload: "attack",
+    });
+
+    expect(res.status).toBe(403);
+    const body = (await res.json()) as { error: string };
+    expect(body.error).toBe("Forbidden access to organization");
+    expect(publishMock).not.toHaveBeenCalled();
+  });
+
+  it("rejects org-less API key with 403", async () => {
+    const publishMock = mock();
+    const app = createApp({
+      auth: { user: undefined, apiKey: { userId: "user_1" } },
+      organization: undefined,
+      eventBus: { publish: publishMock },
+    });
+
+    const res = await postEvent(app, "org_victim", "data", {
+      payload: "attack",
+    });
+
+    expect(res.status).toBe(403);
+    const body = (await res.json()) as { error: string };
+    expect(body.error).toBe("Forbidden access to organization");
+    expect(publishMock).not.toHaveBeenCalled();
+  });
+
+  it("rejects cron injection from different org with 403", async () => {
+    const publishMock = mock();
+    const app = createApp({
+      auth: { user: { id: "user_1" } },
+      organization: { id: "org_attacker" },
+      eventBus: { publish: publishMock },
+    });
+
+    const res = await postEvent(
+      app,
+      "org_victim",
+      "trigger",
+      { recurring: true },
+      "cron=*/5+*+*+*+*",
+    );
+
+    expect(res.status).toBe(403);
+    expect(publishMock).not.toHaveBeenCalled();
+  });
+
+  it("allows authenticated user to publish to own org", async () => {
+    const publishMock = mock();
+    const app = createApp({
+      auth: { user: { id: "user_1" } },
+      organization: { id: "org_1" },
+      eventBus: { publish: publishMock },
+    });
+
+    const res = await postEvent(app, "org_1", "data", {
+      payload: "legitimate",
+    });
+
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as { success: boolean };
+    expect(body.success).toBe(true);
+    expect(publishMock).toHaveBeenCalledTimes(1);
+  });
+});