CWE-339 (PRNG中的种子空间太小) — Vulnerability Class 1

1 vulnerabilities classified as CWE-339 (PRNG中的种子空间太小). AI Chinese analysis included.

MITRE CWE Description

A Pseudo-Random Number Generator (PRNG) uses a relatively small seed space, which makes it more susceptible to brute force attacks. PRNGs are entirely deterministic once seeded, so it should be extremely difficult to guess the seed. If an attacker can collect the outputs of a PRNG and then brute force the seed by trying every possibility to see which seed matches the observed output, then the attacker will know the output of any subsequent calls to the PRNG. A small seed space implies that the attacker will have far fewer possible values to try to exhaust all possibilities.

Common Consequences (1)

Other Varies by Context

Mitigations (2)

Architecture and Design Use well vetted pseudo-random number generating algorithms with adequate length seeds. 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.

Architecture and Design, Requirements Use products or modules that conform to FIPS 140-2 [REF-267] to avoid obvious entropy problems, or use the more recent FIPS 140-3 [REF-1192] if possible.

Examples (1)

This code grabs some random bytes and uses them for a seed in a PRNG, in order to generate a new cryptographic key.

# getting 2 bytes of randomness for the seeding the PRNG seed = os.urandom(2) random.seed(a=seed) key = random.getrandbits(128)

Bad · Python

CVE ID	Title	CVSS	Severity	Published
CVE-2026-2815	Incorrect use of the PUF key for user key generation in EFR32xG27 results in predictable keys — SiSDK	-	-	2026-06-25

Vulnerabilities classified as CWE-339 (PRNG中的种子空间太小) represent 1 CVEs. The CWE taxonomy describes the weakness; review individual CVEs for product-specific impact.