How severe is CVE-2021-3803?

CVE-2021-3803 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-3803 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3803?

CVE-2021-3803 primarily affects Nth-check Project Nth-check. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-3803?

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-2021-3803 published?

CVE-2021-3803 was published on 2021-09-17 and last updated on 2026-06-17.

CVE-2021-3803

CVE-2021-3803 is a high-severity vulnerability in Nth-check Project Nth-check with a CVSS 3.x base score of 7.5. 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-1333.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (79th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-1333
Affected product: Nth-check Project Nth-check
Published: 2021-09-17
Last modified: 2026-06-17

Description

nth-check is vulnerable to Inefficient Regular Expression Complexity

Frequently asked questions

What is CVE-2021-3803?: nth-check is vulnerable to Inefficient Regular Expression Complexity
How severe is CVE-2021-3803?: CVE-2021-3803 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-3803 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3803?: CVE-2021-3803 primarily affects Nth-check Project Nth-check. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-3803?: 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-2021-3803 published?: CVE-2021-3803 was published on 2021-09-17 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:nth-check_project:nth-check:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

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