High severity · published Apr 8, 2026
CVE-2026-39408
Hono has a path traversal in toSSG() allows writing files outside the output directory
7.5
CVSS
0.5%
EPSS
No
On KEV
Description
Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.12, a path traversal issue in toSSG() allows files to be written outside the configured output directory during static site generation. When using dynamic route parameters via ssgParams, specially crafted values can cause generated file paths to escape the intended output directory. This vulnerability is fixed in 4.12.12.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 43% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
HO
hono · honojs
< 4.12.12 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-39408
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-39408
Patch
https://github.com/honojs/hono/commit/b470278920fffcfd6d76002755d6db53db827679
Release Notes
https://github.com/honojs/hono/releases/tag/v4.12.12
Exploit
https://github.com/honojs/hono/security/advisories/GHSA-xf4j-xp2r-rqqx
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