How severe is CVE-2021-40309?

CVE-2021-40309 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-40309 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40309?

CVE-2021-40309 affects Os4ed Opensis. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-40309?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-40309 published?

CVE-2021-40309 was published on 2021-09-24 and last updated on 2026-06-17.

CVE-2021-40309

CVE-2021-40309 is a high-severity vulnerability in Os4ed Opensis with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-89.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.5
EPSS exploit prediction: 2% (75th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-89
Affected product: Os4ed Opensis
Published: 2021-09-24
Last modified: 2026-06-17

Description

A SQL injection vulnerability exists in the Take Attendance functionality of OS4Ed's OpenSIS 8.0. allows an attacker to inject their own SQL query. The cp_id_miss_attn parameter from TakeAttendance.php is vulnerable to SQL injection. An attacker can make an authenticated HTTP request as a user with access to "Take Attendance" functionality to trigger this vulnerability.

Frequently asked questions

What is CVE-2021-40309?: A SQL injection vulnerability exists in the Take Attendance functionality of OS4Ed's OpenSIS 8.0. allows an attacker to inject their own SQL query. The cp_id_miss_attn parameter from TakeAttendance.php is vulnerable to SQL injection. An attacker can make an authenticated HTTP request as a user with access to "Take Attendance" functionality to trigger this vulnerability.
How severe is CVE-2021-40309?: CVE-2021-40309 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-40309 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40309?: CVE-2021-40309 affects Os4ed Opensis. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-40309?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-40309 published?: CVE-2021-40309 was published on 2021-09-24 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:os4ed:opensis:8.0:*:*:*:community:*:*:*

More vulnerabilities in Os4ed Opensis

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CVE-2025-22930 — Critical (CVSS 9.8): OS4ED openSIS v7.0 to v9.1 was discovered to contain a SQL injection vulnerability via the groupid parameter at…
CVE-2025-22929 — Critical (CVSS 9.8): OS4ED openSIS v7.0 to v9.1 was discovered to contain a SQL injection vulnerability via the filter_id parameter at…
CVE-2025-22926 — Critical (CVSS 9.8): An issue in OS4ED openSIS v8.0 through v9.1 allows attackers to execute a directory traversal by sending a crafted POST…
CVE-2025-22928 — Critical (CVSS 9.8): OS4ED openSIS v7.0 to v9.1 was discovered to contain a SQL injection vulnerability via the cp_id parameter at…
CVE-2024-51211 — Critical (CVSS 9.8): SQL injection vulnerability exists in OS4ED openSIS-Classic Version 9.1, specifically in the resetuserinfo.php file.…

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