Vulnerability · Published Apr 8, 2026 · Assigned by GitHub_M

CVE-2026-39408Hono has a path traversal in toSSG() allows writing files outside the output directory

High 7.5

In plain English

A high-severity path traversal in hono from honojs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.5%top 56.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	hono	4.12.12	GHSA-xf4j-xp2r-rqqx

Affected products (as reported)

Vendor	Product	Versions
honojs	hono	< 4.12.12

Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

References

https://github.com/honojs/hono/security/advisories/GHSA-xf4j-xp2r-rqqx x_refsource_CONFIRM
https://github.com/honojs/hono/commit/b470278920fffcfd6d76002755d6db53db827679 x_refsource_MISC
https://github.com/honojs/hono/releases/tag/v4.12.12 x_refsource_MISC