How severe is CVE-2021-39609?

CVE-2021-39609 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-39609 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-39609?

CVE-2021-39609 affects Flatcore Flatcore-cms. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-39609?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-39609 published?

CVE-2021-39609 was published on 2021-08-23 and last updated on 2026-06-17.

CVE-2021-39609

CVE-2021-39609 is a medium-severity vulnerability in Flatcore Flatcore-cms with a CVSS 3.x base score of 5.4. 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-79.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
CVSS v2: 3.5
EPSS exploit prediction: 2% (74th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Flatcore Flatcore-cms
Published: 2021-08-23
Last modified: 2026-06-17

Description

Cross Site Scripting (XSS) vulnerability exiss in FlatCore-CMS 2.0.7 via the upload image function.

Frequently asked questions

What is CVE-2021-39609?: Cross Site Scripting (XSS) vulnerability exiss in FlatCore-CMS 2.0.7 via the upload image function.
How severe is CVE-2021-39609?: CVE-2021-39609 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-39609 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-39609?: CVE-2021-39609 affects Flatcore Flatcore-cms. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-39609?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-39609 published?: CVE-2021-39609 was published on 2021-08-23 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:flatcore:flatcore-cms:2.0.7:*:*:*:*:*:*:*

More vulnerabilities in Flatcore Flatcore-cms

CVE-2021-41403 — Critical (CVSS 9.8): flatCore-CMS version 2.0.8 calls dangerous functions, causing server-side request forgery vulnerabilities.
CVE-2017-7878 — Critical (CVSS 9.8): SQL Injection vulnerability in flatCore version 1.4.6 allows an attacker to read and write to the users database.
CVE-2021-41402 — High (CVSS 8.8): flatCore-CMS v2.0.8 has a code execution vulnerability, which could let a remote malicious user execute arbitrary PHP…
CVE-2017-7877 — High (CVSS 8.8): CSRF vulnerability in flatCore version 1.4.6 allows remote attackers to modify CMS configurations.
CVE-2017-8868 — High (CVSS 7.5): acp/core/files.browser.php in flatCore 1.4.7 allows file deletion via directory traversal in the delete parameter to…
CVE-2017-7879 — High (CVSS 7.5): SQL Injection vulnerability in flatCore version 1.4.6 allows an attacker to read the content database.

All CVEs affecting Flatcore Flatcore-cms →

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