A flaw in Node.js crypto causes the internal entropy caches used by crypto.randomUUID(), crypto.randomUUIDv7(), and crypto.randomInt() to be saved into user-land startup snapshots (--build-snapshot) and single executable applications built with useSnapshot.
If any of these functions, or an API that relies on them such as URL.createObjectURL(), is called while the snapshot is built, every process started from that snapshot returns the same values until the cache is refilled: up to 127 UUIDs and about 1,000 randomInt() values. Identifiers expected to be unique can collide across processes, and values issued by one process can be predicted by observing another.
This vulnerability affects Node.js 26.x, 24.x, and 22.x.
Weakness
The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.
Potential Mitigations
- Use a well-vetted algorithm that is currently considered to be strong by experts in the field, and select well-tested implementations with adequate length seeds.
- In general, if a pseudo-random number generator is not advertised as being cryptographically secure, then it is probably a statistical PRNG and should not be used in security-sensitive contexts.
- Pseudo-random number generators can produce predictable numbers if the generator is known and the seed can be guessed. A 256-bit seed is a good starting point for producing a “random enough” number.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/112.html
- https://cwe.mitre.org/data/definitions/485.html
- https://cwe.mitre.org/data/definitions/59.html