CVE-2026-54286Network attack vector

Unauthenticated static-file disclosure via encoded backslash

Published Jun 22, 2026 · Updated Jun 22, 2026

Path traversal in Hono before 4.12.25 allows remote attackers to read protected static files through encoded backslashes on Windows hosts. The router treats an encoded backslash as part of one URL segment, while serve-static decodes it and the Windows resolver reinterprets it as a path separator. Exposure requires a Windows host using the Node, Bun, or Deno adapter to serve a static subtree guarded by prefix-mounted middleware; reads remain inside the configured root.

CVSS severity5.9
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Hono before 4.12.25 allows remote attackers to read protected static files through encoded backslashes on Windows hosts. The router treats an encoded backslash as part of one URL segment, while serve-static decodes it and the Windows resolver reinterprets it as a path separator. Exposure requires a Windows host using the Node, Bun, or Deno adapter to serve a static subtree guarded by prefix-mounted middleware; reads remain inside the configured root.

The record

CVE
CVE-2026-54286
Published
Jun 22, 2026
Updated
Jun 22, 2026
Vendor
Hono
Product
Hono
Classifications
CWE-22, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.12.25

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hono · Honoversion=< 4.12.25

Published CVSS scores

5.9GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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