CVE-2021-40492

A reflected XSS vulnerability exists in multiple pages in version 22 of the Gibbon application that allows for arbitrary execution of JavaScript (gibbonCourseClassID, gibbonPersonID, subpage, currentDate, or allStudents to index.php).

Published: 2021-09-03 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-40492 is rated Moderate Risk (47.7/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.28%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-40492

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 9.96% 2.28% -7.69%
2 2025-12-28 10.59% 9.96% -0.62%
3 2025-12-27 — 10.59% —

Full EPSS history (24 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-40492

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 2.7 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2021-40492

Affected software / configurations for CVE-2021-40492

Vendor Product Version Raw CPE
gibbonedu gibbon 22.0.00 cpe:2.3:a:gibbonedu:gibbon:22.0.00:*:*:*:*:*:*:*

References for CVE-2021-40492

URL Tags
https://gibbonedu.org/ Vendor Advisory
https://github.com/5qu1n7/CVE-2021-40492 Third Party Advisory
cvelogic Threat Intelligence