CVE-2021-23838 json
An issue was discovered in flatCore before 2.0.0 build 139.
published 2021-01-15 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-10766
- cvss
- 4.8
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.0%
- EPSS 1.0% chance of exploitation in 30 days, percentile 62%
- public exploits
- 0
- none known
Summary
An issue was discovered in flatCore before 2.0.0 build 139. A reflected XSS vulnerability was identified in the media_filter HTTP request body parameter for the acp interface. The affected parameter accepts malicious client-side script without proper input sanitization. For example, a malicious user can leverage this vulnerability to steal cookies from a victim user and perform a session-hijacking attack, which may then lead to unauthorized access to the site.
Exploit prediction
0.99% chance of exploitation in the next 30 days, higher than 62% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- packetstormsecurity.com http://packetstormsecurity.com/files/160936/flatCore-CMS-XSS-File-Disclosure-SQL-Injection.html referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 4.8 | CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N |
| NVD | 2.0 | 3.5 | AV:N/AC:M/Au:S/C:N/I:P/A:N |
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
packetstormsecurity.com
/files/160936/flatCore-CMS-XSS-File-Disclosure-SQL-Injection.html
exploit, third-party-advisory, vdb-entry
-
github.com
/flatCore/flatCore-CMS
product, third-party-advisory
-
sec-consult.com
/vulnerability-lab/
third-party-advisory
Sources
- CVE List CVE-2021-23838
- NVD CVE-2021-23838
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.