crypto: reset random caches across snapshots · nodejs/node@4d6990b · GitHub
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crypto: reset random caches across snapshots
Startup snapshots retain unused randomInt() and UUID cache entries, causing deserialized processes to replay the same random values. Clear the caches after user serialization callbacks and before user deserialization callbacks. The latter also handles caches refilled by microtasks, next ticks, or exit handlers after serialization callbacks. Refs: https://hackerone.com/reports/4059814 Signed-off-by: Filip Skokan <panva.ip@gmail.com> Assisted-by: Codex PR-URL: nodejs-private/node-private#987 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Ruy Adorno <ruy@vlt.sh> CVE-ID: CVE-2026-106074
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4 files changed

Lines changed: 172 additions & 1 deletion

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‎lib/internal/crypto/random.js‎

Lines changed: 30 additions & 0 deletions

‎lib/internal/v8/startup_snapshot.js‎

Lines changed: 16 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -35,8 +35,14 @@ function throwIfBuildingSnapshot(reason) {
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}
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const deserializeCallbacks = [];
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const beforeUserDeserializeCallbacks = [];
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let deserializeCallbackIsSet = false;
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function runDeserializeCallbacks() {
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for (let i = 0; i < beforeUserDeserializeCallbacks.length; i++) {
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const { 0: callback, 1: data } = beforeUserDeserializeCallbacks[i];
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callback(data);
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}
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beforeUserDeserializeCallbacks.length = 0;
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for (let i = 0; i < deserializeCallbacks.length; i++) {
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const { 0: callback, 1: data } = deserializeCallbacks[i];
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callback(data);
@@ -45,6 +51,14 @@ function runDeserializeCallbacks() {
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}
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function addDeserializeCallback(callback, data) {
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addDeserializeCallbackImpl(deserializeCallbacks, callback, data);
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}
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function addBeforeUserDeserializeCallback(callback, data) {
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addDeserializeCallbackImpl(beforeUserDeserializeCallbacks, callback, data);
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}
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function addDeserializeCallbackImpl(callbacks, callback, data) {
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throwIfNotBuildingSnapshot();
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validateFunction(callback, 'callback');
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if (!deserializeCallbackIsSet) {
@@ -55,7 +69,7 @@ function addDeserializeCallback(callback, data) {
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setDeserializeCallback(runDeserializeCallbacks);
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deserializeCallbackIsSet = true;
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}
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deserializeCallbacks.push([callback, data]);
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callbacks.push([callback, data]);
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}
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const serializeCallbacks = [];
@@ -130,4 +144,5 @@ module.exports = {
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isBuildingSnapshot,
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},
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addAfterUserSerializeCallback,
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addBeforeUserDeserializeCallback,
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};

‎test/fixtures/snapshot/crypto-random-cache.js‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,96 @@
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'use strict';
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const assert = require('node:assert');
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const {
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addDeserializeCallback,
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addSerializeCallback,
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setDeserializeMainFunction,
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} = require('node:v8').startupSnapshot;
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// Register before loading crypto to ensure its cleanup takes precedence even
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// over user callbacks that were registered earlier.
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let deserialized;
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addDeserializeCallback(() => {
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deserialized = sample();
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});
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const {
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randomInt,
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randomUUID,
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randomUUIDv7,
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} = require('node:crypto');
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const buildValues = [];
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const max = 2 ** 48 - 1;
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function primeCaches() {
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buildValues.push(
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randomUUID(),
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randomInt(max),
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randomUUID({ disableEntropyCache: true }),
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);
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}
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switch (process.env.NODE_TEST_CRYPTO_RANDOM_MODE) {
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case 'uuid':
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primeCaches();
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break;
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case 'uuidv7':
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buildValues.push(
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randomUUIDv7(),
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randomInt(max),
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randomUUIDv7({ disableEntropyCache: true }),
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);
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break;
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case 'object-url':
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URL.revokeObjectURL(URL.createObjectURL(new Blob(['snapshot'])));
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break;
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case 'async':
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randomInt(max, (err, value) => {
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assert.ifError(err);
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buildValues.push(value);
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});
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break;
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case 'serialize':
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primeCaches();
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// A user callback can refill the caches after an earlier cleanup callback.
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addSerializeCallback(primeCaches);
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break;
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case 'microtask':
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primeCaches();
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addSerializeCallback(() => queueMicrotask(primeCaches));
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break;
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case 'next-tick':
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primeCaches();
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addSerializeCallback(() => process.nextTick(primeCaches));
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break;
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case 'exit':
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primeCaches();
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process.once('exit', primeCaches);
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break;
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case 'unprimed':
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break;
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default:
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assert.fail('Unknown cache priming mode');
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}
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function sample() {
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return {
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uuid: Array.from({ length: 4 }, () => randomUUID()),
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// Exclude the timestamp and version so clock changes cannot hide replay.
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uuidv7: Array.from({ length: 4 }, () => randomUUIDv7().slice(15)),
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webcrypto: Array.from({ length: 4 }, () => globalThis.crypto.randomUUID()),
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int: Array.from({ length: 4 }, () => randomInt(max)),
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};
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}
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setDeserializeMainFunction(async () => {
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const main = sample();
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main.asyncInt = await Promise.all(Array.from({ length: 4 }, () => new Promise((resolve, reject) => {
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randomInt(max, (err, value) => {
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if (err) reject(err);
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else resolve(value);
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});
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})));
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console.log(JSON.stringify({ buildValues, deserialized, main }));
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});

‎test/parallel/test-crypto-random-cache-snapshot.js‎

Lines changed: 30 additions & 0 deletions

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