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Medium 5.9Published Jun 22, 2026

CVE-2026-54286Hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)

Updated under an hour ago ()

Does this affect you?

It affects honojs hono. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, on Windows hosts, an encoded backslash (%5C) in the request path decodes to \, which the Windows path resolver treats as a separator. serve-static then resolves a single URL segment such as admin\secret.txt into a nested file under the root and serves it, letting an attacker read static files meant to be protected behind prefix-mounted middleware. This vulnerability is fixed in 4.12.25.

CVSS
5.9 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness (CWE)
CWE-22
Known exploited
Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days)
Not loaded for this CVE
Assigned by
GitHub_M
NVD analysis
Deferred
Record last updated
Jun 23, 2026
First seen by InfoSec Signals
Oct 9, 2026

Affected products

Affected products
honojs hono
honojs:hono (from the name)
before 4.12.25
CNA record

References

References

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.

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