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CVE-2026-126210

@hono/node-server: Backslash in the request path is parsed as a path separator, bypassing path-based access control at a reverse proxy

5.3 mediumFix available

Medium (5.3) in honojs node-server. Fixed in @hono/node-server 1.19.18, 2.1.6.

On this page
@hono/node-server allows running the Hono application on Node.js. Prior to 1.19.18 and from 2.0.0 until 2.1.6, the server passes a raw request-target containing a backslash in its path to the WHATWG URL parser, which treats the backslash as a path separator and resolves dot segments. A reverse proxy, load balancer, or web application firewall that preserves the backslash and applies path-based rules to the original request can therefore permit a request that the application normalizes to a blocked route. This lets an unauthenticated client reach route content that the upstream component was intended to deny, while Hono application access controls are unaffected because they operate on the normalized path. This issue is fixed in versions 1.19.18 and 2.1.6.

Severity

CVSS 3.1

5.3 medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CWE
CWE-436 Interpretation Conflict
OWASP Top 10
A06:2025 Insecure Design
Published
Assigned by
GitHub_M (CNA)
NVD analysis
Awaiting analysis
Record from
the NVD, synced

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Affected

Versions

From the CNA's record in the CVE List.

ProductAffected
honojs node-server>= 2.0.0, < 2.1.6
honojs node-server< 1.19.18

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-jpvv-r467-5p4wnpm@hono/node-server>=2.0.0 <2.1.62.1.6
GHSA-jpvv-r467-5p4wnpm@hono/node-server<1.19.181.19.18

Attack patterns (CAPEC)

  • CAPEC-34 HTTP Response Splitting Likelihood: Medium · Severity: High
  • CAPEC-105 HTTP Request Splitting Likelihood: Medium · Severity: High
  • CAPEC-273 HTTP Response Smuggling Likelihood: Medium · Severity: High

The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.

References

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