CVE-2026-27959
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
koanpm | >= 3.0.0, < 3.1.2 | 3.1.2 |
koanpm | < 2.16.4 | 2.16.4 |
Affected products
3Patches
Vulnerability mechanics
References
5- github.com/koajs/koa/commit/55ab9bab044ead4e82c70a30a4f9dc0fc9c1b6dfnvdPatchWEB
- github.com/koajs/koa/commit/b76ddc01fdb703e51652b0fd131d16394cadcfebnvdPatchWEB
- github.com/koajs/koa/security/advisories/GHSA-7gcc-r8m5-44qmnvdExploitVendor AdvisoryWEB
- github.com/advisories/GHSA-7gcc-r8m5-44qmghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-27959ghsaADVISORY
News mentions
0No linked articles in our index yet.