Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.13.16, mount() and app.mount() can remove a dynamic mount prefix using the route-pattern length rather than the matched-prefix length, allowing a crafted path to be forwarded as a protected inner route while the outer application routes the original path. Since 4.12.21, rebuilding the forwarded URL from the decoded pathname can also convert a decoded backslash to a slash and collapse parent-directory segments, again causing the mounted application to receive a protected path. An unauthenticated client can use either applicable path transformation to reach a mounted route without authentication or authorization middleware scoped to a subpath inside the mount prefix. This issue is fixed in version 4.13.16.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-288"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126357.json"
}{
"extracted_events": [
{
"range": [
{
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},
{
"fixed": "4.13.16"
}
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"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
},
{
"range": [
{
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}
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"source": "REFERENCES_COMMIT"
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{
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}