Vulnerability · Published Aug 7, 2026 · Assigned by GitHub_M
CVE-2026-71851crypto-js: Insufficient Entropy in Cryptographic Secret Generation via Vulnerable CryptoJS Dependency Chain
Critical 9.0
In plain English
A critical-severity security flaw in crypto-js from brix. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 46% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | cryptojs | no fix listed | DEBIAN-CVE-2026-71851 |
| Ubuntu:24.04:LTS | cryptojs | no fix listed | UBUNTU-CVE-2026-71851 |
| npm | crypto-js | 4.0.0 | GHSA-rg76-677x-56q9 |
Affected products (as reported)
Weakness: CWE-331, CWE-334, CWE-338 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
References
- https://github.com/brix/crypto-js/security/advisories/GHSA-rg76-677x-56q9 x_refsource_CONFIRM
- https://github.com/brix/crypto-js/commit/b405ff597fb3ac76a7bdfbc72dca10ba1079b1d5 x_refsource_MISC
- https://www.coinspect.com/blog/ill-bloom-investigation x_refsource_MISC