Next.js is a React framework for building full-stack web applications. To mitigate CVE-2025-29927, Next.js validated the x-middleware-subrequest-id which persisted across multiple incoming requests. However, this subrequest ID is sent to all requests, even if the destination is not the same host as the Next.js application. Initiating a fetch request to a third-party within Middleware will send the x-middleware-subrequest-id to that third party. This vulnerability is fixed in 12.3.6, 13.5.10, 14.2.26, and 15.2.4.
{
"cwe_ids": [
"CWE-200"
]
}{
"versions": [
{
"introduced": "0"
},
{
"last_affected": "= 12.3.5"
}
]
}{
"versions": [
{
"introduced": "0"
},
{
"last_affected": "= 13.5.9"
}
]
}