Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2021-3990

23
FAUCET Score

CVE-2021-3990 describes a vulnerability in showdoc, where it utilizes a cryptographically weak pseudo-random number generator (PRNG). This medium-severity vulnerability (CVSS 6.5) can be exploited over the network with low attack complexity, potentially leading to high confidentiality impact if a user interacts with a malicious link. Currently, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 2.9.13CPE matchmatch criteria
cpe:2.3:a:showdoc:showdoc:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

6.5MEDIUM

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
LOW
Exploitability Score
2.2
Impact Score
3.7
CvssVersion
3.0

Exploit Intelligence

EPSS Score
0.86%
Probability of exploitation in next 30 days
EPSS Percentile
54.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0086 is in the 65th percentile among its peer group of 26,221 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

composerpatch availablevia ghsa
Product: showdoc/showdocFixed in: 2.9.13
github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

composerGHSA-vrgh-5w3c-ggf8medium

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

Dec 3, 2021

References

github.com / star7th/showdoc/commit/a9886f26c08225e0adca75c67dfca3f7c42b87d0
PatchThird Party Advisory
huntr.dev / bounties/0680067d-56a7-4412-b06e-a267e850ae9f
ExploitPatchThird Party Advisory