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Fencer Vulns
medium 6.5

CVE-2021-3990 json

Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) in star7th/showdoc

published 2021-12-01 4 y ago modified 2026-06-17 4 mo ago also GHSA-vrgh-5w3c-ggf8 , EUVD-2021-2596

cvss
6.5
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits
0
none known

Summary

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

Patch / fix

  • packagist showdoc/showdoc 2.9.13
  • star7th star7th/showdoc 2.9.13

Exploit prediction

0.89% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • huntr.dev https://huntr.dev/bounties/0680067d-56a7-4412-b06e-a267e850ae9f referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 6.5 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
packagist showdoc/showdoc
<2.9.13
2.9.13

Affected products

  • star7th star7th/showdoc

Classification

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

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.