crypto-js: Insufficient Entropy in Cryptographic Secret Generation via Vulnerable CryptoJS Dependency Chain

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

crypto-js is a JavaScript library of crypto standards. Versions of crypto-js prior to 4.0.0 generate randomness in CryptoJS.lib.WordArray.random() using a custom variation of the Multiply-With-Carry pseudorandom number generator, seeded from Math.random(), instead of a cryptographically secure source. This generator was introduced in version 3.1.2-4 and remained present in nearly every 3.x release. Nominal requests for 128 or 256 bits of entropy through this function produce effective search spaces of approximately 2 to the 39th and 2 to the 47th possibilities, small enough to enumerate on commodity hardware. Downstream wallet applications that used CryptoJS.lib.WordArray.random() as the entropy source for BIP39 recovery phrases are affected, and an attacker who enumerates the reduced output space can recover the resulting private keys and control the associated funds. This issue is fixed in version 4.0.0.

Source published

7 Aug 2026 18:48:08 UTC

Source modified

8 Aug 2026 03:05:53 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 9.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

crypto-js is a JavaScript library of crypto standards. Versions of crypto-js prior to 4.0.0 generate randomness in CryptoJS.lib.WordArray.random() using a custom variation of the Multiply-With-Carry pseudorandom number generator, seeded from Math.random(), instead of a cryptographically secure source. This generator was introduced in version 3.1.2-4 and remained present in nearly every 3.x release. Nominal requests for 128 or 256 bits of entropy through this function produce effective search spaces of approximately 2 to the 39th and 2 to the 47th possibilities, small enough to enumerate on commodity hardware. Downstream wallet applications that used CryptoJS.lib.WordArray.random() as the entropy source for BIP39 recovery phrases are affected, and an attacker who enumerates the reduced output space can recover the resulting private keys and control the associated funds. This issue is fixed in version 4.0.0.

Source published

7 Aug 2026 19:18:54 UTC

Source modified

24 Oct 2026 15:10:00 UTC

Observed here

25 Oct 2026 15:19:03 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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CVSS 3.1 · [email protected] · Secondary · 9.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

### Summary `CryptoJS.lib.WordArray.random()` in affected versions is not a cryptographically secure random number generator. Nominal requests for 128 or 256 bits of entropy produce effective search spaces of approximately 2^39 and 2^47 possibilities — small enough to enumerate on commodity hardware. Coinspect's [Ill Bloom](https://www.coinspect.com/blog/ill-bloom-investigation/) investigation confirmed that downstream wallet applications used this function as the entropy source for BIP39 recovery phrases. **An application is affected only if it uses the vulnerable function to generate security-sensitive values.** Merely depending on `crypto-js < 4.0.0` is not sufficient to be exploitable. ### Details The affected implementation used a custom variation of George Marsaglia's Multiply-With-Carry PRNG, seeded from `Math.random()`. It was introduced in 3.1.2-4 (June 2014, commit brix/crypto-js@ff1f003) in response to issue \#7, and was present in every 3.x release except 3.2.0 and 3.2.1. That **change was reverted in 3.3.0** because it was considered a breaking change, so projects tracking the 3.x line could resolve to newer versions that still contained the weak generator. 4.0.0 replaced the generator with the platform's native cryptographic API. Applying PBKDF2, another KDF, or a cryptographic hash after the vulnerable generator does not restore missing entropy. ### Proof of concept Coinspect reproduced the attack end to end: 1. Reimplemented the affected `WordArray.random()` behavior. 2. Enumerated the feasible outputs of the underlying PRNG. 3. Converted candidate entropy values into valid BIP39 recovery phrases. 4. Derived private keys and addresses across the relevant derivation paths and networks. 5. Compared derived addresses against public blockchain data. 6. Recovered the private keys controlling funded addresses. ### Impact An attacker can enumerate the reduced output space and recover security-sensitive values generated through the affected function. Coinspect documented coordinated drain waves affecting addresses derived from vulnerable recovery phrases. As of July 13, 2026, the measured lower bound of stolen assets across the two events was approximately $5M. The consequences are persistent: * Updating an affected library or wallet does not strengthen a previously generated secret. * Importing the same recovery phrase into an updated software or hardware wallet does not remediate the issue. * Previously generated secrets may remain exploitable indefinitely. * Future deposits to an affected address may also be stolen. * Assets may remain exposed across networks or derivation paths that have not yet shown suspicious activity. ### Remediation **For projects:** 1. Upgrade `crypto-js` to version `4.0.0` or later. Where possible, replace CryptoJS randomness with the native Web Crypto API or Node.js `crypto` module. 2. Audit direct, downstream, and transitive dependencies for versions of `crypto-js` matching `< 4.0.0`. 3. Determine whether `CryptoJS.lib.WordArray.random()` was used to generate any security-sensitive values. 4. Identify the time periods and application versions during which the vulnerable generation path was present. 5. Treat all long-term secrets generated through an affected path as compromised and rotate them. 6. Notify affected users that installing an update is insufficient when a long-term secret was generated by the vulnerable code. **For wallet users:** create a new wallet with a newly generated recovery phrase from a trustworthy source and migrate assets to addresses derived from it. Do not import the existing recovery phrase into the new wallet. ### Public address checker Coinspect provides a public checker for addresses identified in the known Ill Bloom exposed-address datasets: [https://illbloom.org/](https://illbloom.org/) Only public blockchain addresses should be entered. Users must **never enter a recovery phrase**, seed phrase, mnemonic, private key, password, or wallet backup file. A match indicates that funds controlled by the same recovery phrase may be at immediate risk. A negative result only means that the submitted address was not found in the currently published datasets. ### References * Ill Bloom research site and public address checker: [https://illbloom.org/](https://illbloom.org/) * Coinspect investigation overview: [https://www.coinspect.com/blog/ill-bloom-investigation/](https://www.coinspect.com/blog/ill-bloom-investigation/) * CryptoJS issue \#7 — `randomBytes is not random enough`: [https://github.com/brix/crypto-js/issues/7](https://github.com/brix/crypto-js/issues/7) * Commit introducing the MWC-based implementation: [https://github.com/brix/crypto-js/commit/ff1f0032ff58aedfcc44eb6aa7b2c78207a98009](https://github.com/brix/crypto-js/commit/ff1f0032ff58aedfcc44eb6aa7b2c78207a98009) * Changes between CryptoJS `3.3.0` and `4.0.0`: [https://github.com/brix/crypto-js/compare/3.3.0...4.0.0](https://github.com/brix/crypto-js/compare/3.3.0...4.0.0) * Downstream `ferrumnet/bip39` fork: [https://github.com/ferrumnet/bip39](https://github.com/ferrumnet/bip39)

Source published

7 Aug 2026 18:48:59 UTC

Source modified

7 Aug 2026 19:10:56 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Publisher rating · CRITICAL