What is CVE-2021-3990?

CVE-2021-3990 is a medium-severity vulnerability in Showdoc, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 6.5/10. Published 2021-12-01.

How severe is CVE-2021-3990?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Showdoc

CVE-2021-3990

showdoc is vulnerable to Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

Published 2021-12-01 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.009 (57.8th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 57.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: +0.000

Affected products

Showdoc
Star7th Star7th/showdoc — versions unspecified

Weakness classification (CWE)

CWE-338 — Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

References

huntr.dev/bounties/0680067d-56a7-4412-b06e-a267e850ae9f (Exploit, Patch, Third Party Advisory)
github.com/star7th/showdoc/commit/a9886f26c08225e0adca75c67dfca3f7c42b87d0 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-3990?: CVE-2021-3990 is a medium-severity vulnerability in Showdoc, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 6.5/10. Published 2021-12-01.
How severe is CVE-2021-3990?: Medium severity. CVSS v3 base score is 6.5 out of 10.