RCE in Basercms
CVE-2026-21861
baserCMS is a website development framework. Prior to version 5.2.3, baserCMS contains an OS command injection vulnerability in the core update functionality. An authenticated administrator can execute arbitrary OS commands on the server due to improper handling of user-controlled input that is directly passed to exec() without sufficient validation or escaping. This issue has been patched in version 5.2.3.
Vulnerability class: Command Injection (OS Command Injection)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.023 (82.5th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 82nd percentile — 82.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.023 · newest: 0.023 · change: 0.000
Affected products
- Basercms
- Baserproject Basercms — versions < 5.2.3
Weakness classification (CWE)
References
- github.com/baserproject/basercms/security/advisories/GHSA-qxmc-6f24-g86g (Exploit, Vendor Advisory)
- basercms.net/security/JVN_20837860 (Vendor Advisory)
- github.com/baserproject/basercms/releases/tag/5.2.3 (Release Notes)
Frequently asked questions
- What is CVE-2026-21861?
- CVE-2026-21861 is a critical-severity vulnerability in Basercms, classified under OS Command Injection. CVSS score: 9.1/10. Published 2026-03-31.
- How severe is CVE-2026-21861?
- Critical severity. CVSS v3 base score is 9.1 out of 10.