{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-27588","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-02-20T17:40:28.450Z","datePublished":"2026-02-24T16:28:28.106Z","dateUpdated":"2026-02-27T20:47:36.164Z"},"containers":{"cna":{"title":"Caddy: MatchHost becomes case-sensitive for large host lists (>100), enabling host-based route/auth bypass","problemTypes":[{"descriptions":[{"cweId":"CWE-178","lang":"en","description":"CWE-178: Improper Handling of Case Sensitivity","type":"CWE"}]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":7.7,"baseSeverity":"HIGH","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P","version":"4.0"}}],"references":[{"name":"https://github.com/caddyserver/caddy/security/advisories/GHSA-x76f-jf84-rqj8","tags":["x_refsource_CONFIRM"],"url":"https://github.com/caddyserver/caddy/security/advisories/GHSA-x76f-jf84-rqj8"},{"name":"https://github.com/caddyserver/caddy/releases/tag/v2.11.1","tags":["x_refsource_MISC"],"url":"https://github.com/caddyserver/caddy/releases/tag/v2.11.1"}],"affected":[{"vendor":"caddyserver","product":"caddy","versions":[{"version":"< 2.11.1","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-02-24T16:28:28.106Z"},"descriptions":[{"lang":"en","value":"Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, Caddy's HTTP `host` request matcher is documented as case-insensitive, but when configured with a large host list (>100 entries) it becomes case-sensitive due to an optimized matching path. An attacker can bypass host-based routing and any access controls attached to that route by changing the casing of the `Host` header. Version 2.11.1 contains a fix for the issue."}],"source":{"advisory":"GHSA-x76f-jf84-rqj8","discovery":"UNKNOWN"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-02-27T20:47:27.256996Z","id":"CVE-2026-27588","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-02-27T20:47:36.164Z"}}]}}