CVE-2021-28833 json
qiita-markdown Cross-site Scripting vulnerability
published 2021-06-21 5 y ago modified 2026-06-17 4 mo ago also GHSA-9p29-94hp-8rvc , EUVD-2021-1664
- cvss
- 6.1
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 54%
- public exploits
- 0
- none known
Summary
Increments Qiita::Markdown before 0.34.0 allows XSS via a crafted gist link, a different vulnerability than CVE-2021-28796.
Patch / fix
- rubygems qiita-markdown 0.34.0
- increments qiita::markdown 0.34.0
Exploit prediction
0.74% chance of exploitation in the next 30 days, higher than 54% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| 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 |
| GitHub | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| rubygems | qiita-markdown | <0.34.0 |
0.34.0 |
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
github.com
/increments/qiita-markdown/commit/b5d4e60bf537ceb177e70bf91653d29575e1aa21
web
-
github.com
/increments/qiita-markdown/releases
web, third-party-advisory
-
vuln.ryotak.me
/advisories/50
web, third-party-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2021-28833
advisory
-
github.com
/increments/qiita-markdown
package
-
github.com
/increments/qiita-markdown/compare/v0.33.0...v0.34.0
web
Sources
- CVE List CVE-2021-28833
- GitHub Advisory GHSA-9p29-94hp-8rvc
- NVD CVE-2021-28833
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.