What is CVE-2021-40310?

CVE-2021-40310 is a medium-severity vulnerability in Os4ed Opensis, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-09-24.

How severe is CVE-2021-40310?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Os4ed Opensis

CVE-2021-40310

OpenSIS Community Edition version 8.0 is affected by a cross-site scripting (XSS) vulnerability in the TakeAttendance.php via the cp_id_miss_attn parameter.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-09-24 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.008 (57.2th percentile), scored 2026-10-21.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 57th percentile — 57.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Os4ed Opensis — versions 8.0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/OS4ED/openSIS-Classic (Product, Third Party Advisory)
www.youtube.com/watch (Exploit, Third Party Advisory)
github.com/MiSERYYYYY/Vulnerability-Reports-and-Disclosures/blob/main/OpenSIS-C… (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-40310?: CVE-2021-40310 is a medium-severity vulnerability in Os4ed Opensis, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-09-24.
How severe is CVE-2021-40310?: Medium severity. CVSS v3 base score is 5.4 out of 10.