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🛡️ CVE-2026-29045 — hono

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-177 OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Hono vulnerable to arbitrary file access via serveStatic vulnerability

Summary

When using serveStatic together with route-based middleware protections (e.g. app.use('/admin/*', ...)), inconsistent URL decoding allowed protected static resources to be accessed without authorization.

The router used decodeURI, while serveStatic used decodeURIComponent. This mismatch allowed paths containing encoded slashes (%2F) to bypass middleware protections while still resolving to the intended filesystem path.

Details

The routing layer preserved %2F as a literal string, while serveStatic decoded it into / before resolving the file path.

Example:

Request: /admin%2Fsecret.html

  • Router sees: /admin%2Fsecret.html → does not match /admin/*
  • Static handler resolves: /admin/secret.html

As a result, static files under the configured static root could be served without triggering route-based protections.

This only affects applications that both:

  • Protect subpaths using route-based middleware, and
  • Serve files from the same static root using serveStatic.

This does not allow access outside the static root and is not a path traversal vulnerability.

Impact

An unauthenticated attacker could bypass route-based authorization for protected static resources by supplying paths containing encoded slashes.

Applications relying solely on route-based middleware to protect static subpaths may have exposed those resources.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity none, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: None.
  • Availability impact: None.

Weakness class

CVE-2026-29045 is classified as CWE-177: Improper Handling of URL Encoding (Hex Encoding). The product does not properly handle when all or part of an input has been URL encoded.

Affected software

CVE-2026-29045 is recorded against 1 package.

  • hono

Timeline and source

Published on 4 March 2026 and last revised on 8 July 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from OSV.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Package)

Other advisories for this package

hono has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-177: Improper Handling of URL Encoding (Hex Encoding)) in other software:

CVE-2026-29045 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CWE CWE-177
Public Exploit ✅ No
Source OSV
Published 2026-03-04
Updated 2026-08-20
Modified 2026-07-08

Affected Packages

Software From version Fixed in
hono — —

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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