Cyber Resilience

CVE-2021-3831

MediumPublic PoC

Published: 14 December 2021

Published
14 December 2021
Modified
21 November 2024
KEV Added
Patch
CVSS Score v3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS Score 0.2661 96.5th percentile
Risk Priority 28 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-3831 is a medium-severity Cross-site Scripting (CWE-79) vulnerability in Gnuboard Gnuboard5. Its CVSS base score is 6.1 (Medium).

Operationally, ranked in the top 3.5% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability details

gnuboard5 is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

gnuboard
gnuboard5
≤ 5.4.20

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-79

Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.

addresses: CWE-79

Validates web inputs to reject script-related content that could produce XSS.

addresses: CWE-79

Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.

References