How severe is CVE-2021-3317?

CVE-2021-3317 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-2021-3317 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 41% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3317?

CVE-2021-3317 affects Klogserver Klog Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3317?

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-2021-3317 published?

CVE-2021-3317 was published on 2021-01-26 and last updated on 2026-06-17.

CVE-2021-3317

CVE-2021-3317 is a high-severity vulnerability in Klogserver Klog Server with a CVSS 3.x base score of 8.8. Its EPSS exploit-prediction score of 41% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-78.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.5
EPSS exploit prediction: 41% (99th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-78
Affected product: Klogserver Klog Server
Published: 2021-01-26
Last modified: 2026-06-17

Description

KLog Server through 2.4.1 allows authenticated command injection. async.php calls shell_exec() on the original value of the source parameter.

Frequently asked questions

What is CVE-2021-3317?: KLog Server through 2.4.1 allows authenticated command injection. async.php calls shell_exec() on the original value of the source parameter.
How severe is CVE-2021-3317?: CVE-2021-3317 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-2021-3317 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 41% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3317?: CVE-2021-3317 affects Klogserver Klog Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3317?: 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-2021-3317 published?: CVE-2021-3317 was published on 2021-01-26 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:klogserver:klog_server:*:*:*:*:*:*:*:*

More vulnerabilities in Klogserver Klog Server

CVE-2020-35729 — Critical (CVSS 9.8): KLog Server 2.4.1 allows OS command injection via shell metacharacters in the actions/authenticate.php user parameter.

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