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
- Medium 5.3
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.
Key facts
- Published
- 12 Nov 2026
- Last changed
- 13 Nov 2026
- Assigned by
- GitHub_M
- EPSS
- 0.375% likely to be exploited in the next 30 days, higher than 31.963% of CVEs (scores for 15 Nov 2026)
- SSVC (CISA)
- Exploitation: none; Automatable: yes; Technical impact: partial
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 5.3CVSS 3.1, Mediumfrom the CNA (GitHub_M)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.
No explicit remediation statement is available on this page yet. Consult the original record and vendor references before choosing a fix.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Affected products
| Vendor | Product | Versions |
|---|---|---|
| honojs | node-server |
|
Timeline
- 12 Nov 2026 Published
Weakness
References
- https://github.com/honojs/node-server/security/advisories/GHSA-jpvv-r467-5p4w
- https://github.com/honojs/node-server/commit/3868998a805ae79216535ad3986c1e7228dee313
- https://github.com/honojs/node-server/commit/fb97395ec36af66567c76976e741110b02804d1c
- https://github.com/honojs/node-server/releases/tag/v1.19.18
- https://github.com/honojs/node-server/releases/tag/v2.1.6