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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-126210
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-12 22:19:18 UTC
Updated2026-11-12 22:19:18 UTC
Description@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.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Problem Types: CWE-436 | CWE-436 CWE-436: Interpretation Conflict

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Honojs Node-server affected >= 2.0.0, < 2.1.6 Not specified
CNA Honojs Node-server affected < 1.19.18 Not specified

References

ReferenceSourceLinkTags
github.com/honojs/node-server/commit/fb97395ec36af66567c76976e741110b028... [email protected] github.com
github.com/honojs/node-server/releases/tag/v1.19.18 [email protected] github.com
github.com/honojs/node-server/security/advisories/GHSA-jpvv-r467-5p4w [email protected] github.com
github.com/honojs/node-server/commit/3868998a805ae79216535ad3986c1e7228d... [email protected] github.com
github.com/honojs/node-server/releases/tag/v2.1.6 [email protected] github.com
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