CVE-2026-27959

{"id": "CVE-2026-27959", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 3.9}]}, "published": "2026-02-26T02:16:23.317", "references": [{"url": "https://github.com/koajs/koa/commit/55ab9bab044ead4e82c70a30a4f9dc0fc9c1b6df", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/koajs/koa/commit/b76ddc01fdb703e51652b0fd131d16394cadcfeb", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/koajs/koa/security/advisories/GHSA-7gcc-r8m5-44qm", "tags": ["Exploit", "Vendor Advisory"], "source": "security-advisories@github.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-20"}]}, {"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "descriptions": [{"lang": "en", "value": "Koa is middleware for Node.js using ES2017 async functions. Prior to versions 3.1.2 and 2.16.4, Koa's `ctx.hostname` API performs naive parsing of the HTTP Host header, extracting everything before the first colon without validating the input conforms to RFC 3986 hostname syntax. When a malformed Host header containing a `@` symbol is received, `ctx.hostname` returns `evil[.]com` - an attacker-controlled value. Applications using `ctx.hostname` for URL generation, password reset links, email verification URLs, or routing decisions are vulnerable to Host header injection attacks. Versions 3.1.2 and 2.16.4 fix the issue."}], "lastModified": "2026-02-28T00:55:26.413", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:koajs:koa:*:*:*:*:*:node.js:*:*", "vulnerable": true, "matchCriteriaId": "47B8F313-898E-4B6D-936A-8F35AC7E7C20", "versionEndExcluding": "2.16.14"}, {"criteria": "cpe:2.3:a:koajs:koa:*:*:*:*:*:node.js:*:*", "vulnerable": true, "matchCriteriaId": "D5367576-B8D5-45EE-9214-D40A4E6E1049", "versionEndExcluding": "3.1.2", "versionStartIncluding": "3.0.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}