What is CVE-2021-27811?

CVE-2021-27811 is a high-severity vulnerability in Qibosoft, classified under Code Injection. CVSS score: 7.2/10. Published 2021-05-21.

How severe is CVE-2021-27811?

High severity. CVSS v3 base score is 7.2 out of 10.

RCE in Qibosoft

CVE-2021-27811

A code injection vulnerability has been discovered in the Upgrade function of QibosoftX1 v1.0. An attacker is able execute arbitrary PHP code via exploitation of client_upgrade_edition.php and Upgrade.php.

Vulnerability class: RCE (Remote Code Execution)

Published 2021-05-21 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.012 (66.9th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 67th percentile — 66.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000

Affected products

Qibosoft — versions 1.0

Weakness classification (CWE)

CWE-94 — Code Injection

References

github.com/whiskey-jj/w2s2x2222.github.io/issues/2 (Exploit, Third Party Advisory, Issue Tracking)
www.cnvd.org.cn/flaw/show/2297879 (Third Party Advisory)

Frequently asked questions

What is CVE-2021-27811?: CVE-2021-27811 is a high-severity vulnerability in Qibosoft, classified under Code Injection. CVSS score: 7.2/10. Published 2021-05-21.
How severe is CVE-2021-27811?: High severity. CVSS v3 base score is 7.2 out of 10.