CVE-2021-3831 json
Cross-site Scripting (XSS) - Reflected in gnuboard/gnuboard5
published 2021-12-14 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-27078
- cvss
- 7.1
- version 3.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.8%
- EPSS 1.8% chance of exploitation in 30 days, percentile 79%
- public exploits
- 0
- none known, plus a Nuclei check
Summary
gnuboard5 is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Patch / fix
- gnuboard gnuboard/gnuboard5 5.4.20
Exploit prediction
1.84% chance of exploitation in the next 30 days, higher than 79% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- Nuclei template Gnuboard 5 - Cross-Site Scripting nuclei detection template
- huntr.dev https://huntr.dev/bounties/25775287-88cd-4f00-b978-692d627dff04 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.0 | 7.1 | CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H |
| NVD | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| NVD | 2.0 | 4.3 | AV:N/AC:M/Au:N/C:N/I:P/A:N |
Affected products
- gnuboard gnuboard/gnuboard5
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
github.com
/gnuboard/gnuboard5/commit/2e81619ea87bc9c0b4a073d8df3c7693a6fdbf0d
patch, third-party-advisory
-
huntr.dev
/bounties/25775287-88cd-4f00-b978-692d627dff04
exploit, patch, third-party-advisory
Sources
- CVE List CVE-2021-3831
- NVD CVE-2021-3831
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.