What’s Vulnerable › Vulnerabilities

CVE-2021-33318

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2022-05-16 · updated 2026-06-17
• Weakness: CWE-704

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.

Affected products

• Ipmatcher Project Ipmatcher: through 1.0.4.1
• Watsonwebserver Project Watsonwebserver: through 4.1.3

References

• https://github.com/jchristn/IpMatcher
• https://github.com/jchristn/IpMatcher/commit/81d77c2f33aa912dbd032b34b9e184fc6e041d89
• https://github.com/jchristn/WatsonWebserver
• https://github.com/kaoudis/advisories/blob/main/0-2021.md
• https://github.com/jchristn/IpMatcher
• https://github.com/jchristn/IpMatcher/commit/81d77c2f33aa912dbd032b34b9e184fc6e041d89
• https://github.com/jchristn/WatsonWebserver
• https://github.com/kaoudis/advisories/blob/main/0-2021.md

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