CVE-2026-27959 - Koa has Host Header Injection via `ctx.hostname`

CVE ID : CVE-2026-27959 Published : Feb. 26, 2026, 2:16 a.m. | 50 minutes ago Description : 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. Severity: 7.5 | HIGH Visit the link for more details, such as CVSS details, affected products, timeline, and more...