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Fencer Intel
medium 5.4

CVE-2026-126344 json

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

published 11d ago modified yesterday also EUVD-2026-124722 , GHSA-7v5p-43qr-wch5

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository honojs/node-server. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
5.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

@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.

Patch / fix

  • npm @hono/node-server 2.1.6

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
yesterday

Exploit prediction

0.16% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-13).

CVSS scores

assigned by version score vector
CNA 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm @hono/node-server
>=2.0.0, <2.1.6
2.1.6

Affected products

  • honojs node-server

Classification

Weakness
  • CWE-1385 Missing Origin Validation in WebSockets

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of honojs/node-server published their own advisory on GitHub. Reviewed sources take precedence over it.