CVE-2021-33318
CVSS v3
9.8
CRITICAL
EPSS Score
2.0 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
Description
An Input Validation Vulnerability exists in Joel Christner .NET C# packages WatsonWebserver, IpMatcher 1.0.4.1 and below (IpMatcher) and 4.1.3 and below (WatsonWebserver) due to insufficient validation of input IP addresses and netmasks against the internal Matcher list of IP addresses and subnets.
Technical details
- Published
- 2022-05-16
Frequently asked questions
What is CVE-2021-33318?
An Input Validation Vulnerability exists in Joel Christner .NET C# packages WatsonWebserver, IpMatcher 1.0.4.1 and below (IpMatcher) and 4.1.3 and below (WatsonWebserver) due to insufficient validation of input IP addresses and netmasks against the internal Matcher list of IP addresses and subnets.
Is CVE-2021-33318 actively exploited?
Active exploitation of CVE-2021-33318 has not been confirmed. Its EPSS score was 2.0% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2021-33318?
CVE-2021-33318 has a CVSS v3 base score of 9.8 (CRITICAL severity).
Is CVE-2021-33318 affecting your environment?
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