{"action":"Upgrade koa to 2.16.4 or later.","affected":[{"fixed":"3.1.2","introduced":"3.0.0"},{"fixed":"2.16.4","introduced":"0"}],"component":"koa","cve_ids":["CVE-2026-27959"],"ecosystem":"npm","epss":0.00391,"exploited":false,"fixed_versions":["3.1.2","2.16.4"],"ghsa_id":"GHSA-7gcc-r8m5-44qm","id":"tcs_01M5KF9YJGGTXS98FEFZN1T8NG","modified_at":"2026-02-26T23:41:18.848183Z","published_at":"2026-02-26T22:42:57Z","references":["https://osv.dev/vulnerability/GHSA-7gcc-r8m5-44qm","https://github.com/koajs/koa/security/advisories/GHSA-7gcc-r8m5-44qm","https://nvd.nist.gov/vuln/detail/CVE-2026-27959","https://github.com/koajs/koa/commit/55ab9bab044ead4e82c70a30a4f9dc0fc9c1b6df","https://github.com/koajs/koa/commit/b76ddc01fdb703e51652b0fd131d16394cadcfeb","https://github.com/koajs/koa"],"severity":{"label":"high","score":7.5},"sources":[{"source":"osv","source_id":"GHSA-7gcc-r8m5-44qm","url":"https://osv.dev/vulnerability/GHSA-7gcc-r8m5-44qm"}],"summary":"Koa has Host Header Injection via ctx.hostname"}