# CVE-2026-126344: @hono/node-server: WebSocket upgrade request-target starting with `//` replaces the host in `c.req.url`, bypassing `Origin` checks

Status: published. Published: 2026-11-12. Updated: 2026-11-13.

@hono/node-server allows running the Hono application on Node.js. From 2.0.0 until 2.1.6, the WebSocket upgrade path resolves a raw request-target beginning with // against a base URL built from the Host header, causing the WHATWG URL parser to treat the request-target as a network-path reference and replace the host in c.req.url. Routing still uses the local WebSocket path, so an application that compares the Origin header with the origin of c.req.url, including checks implemented with csrf(), compares an attacker's origin with itself and accepts the connection. A page on another site can consequently open a WebSocket with the victim's cookies and read and send messages when the application uses upgradeWebSocket and trusts the host in c.req.url. Ordinary HTTP requests are not affected. This issue is fixed in version 2.1.6.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- honojs / node-server: >= 2.0.0, < 2.1.6 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 5.4 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N; source: CNA: GitHub_M

- CVSS 3.1: 5.4 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-1385

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/honojs/node-server/security/advisories/GHSA-7v5p-43qr-wch5 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/honojs/node-server/commit/cfaa79f76dbb0fe9f539438c0c585d94ed7cd01f (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/honojs/node-server/releases/tag/v2.1.6 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/honojs/node-server/commit/cfaa79f76dbb0fe9f539438c0c585d94ed7cd01f (security-advisories@github.com)

- https://github.com/honojs/node-server/releases/tag/v2.1.6 (security-advisories@github.com)

- https://github.com/honojs/node-server/security/advisories/GHSA-7v5p-43qr-wch5 (security-advisories@github.com)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-126344; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-126344; retrieved 2026-11-13; source updated 2026-11-12

Revision: fe8f50b4068420e6d5e9b87d40dcb59c3263a11c913ce5da2047aaa98338c0dc

Canonical: https://y2.dev/cve/CVE-2026-126344

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