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[GHSA-p3f5-w63m-mxph] webpack-dev-middleware resolves a request to a local file... #9696

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[GHSA-p3f5-w63m-mxph] webpack-dev-middleware resolves a request to a local file... #9696

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30 changes: 21 additions & 9 deletions advisories/unreviewed/2026/08/GHSA-p3f5-w63m-mxph/GHSA-p3f5-w63m-mxph.json
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{
"schema_version": "1.4.0",
"id": "GHSA-p3f5-w63m-mxph",
"modified": "2026-08-24T15:31:51Z",
"modified": "2026-08-24T15:31:52Z",
"published": "2026-08-24T15:31:51Z",
"aliases": [
"CVE-2026-76844"
],
"summary": "Path Traversal in webpack-dev-middleware",
"details": "webpack-dev-middleware resolves a request to a local file in getFilenameFromUrl by testing the request pathname against a traversal guard and then slicing it at a fixed character offset. The guard, UP_PATH_REGEXP applied to path.normalize(`./${pathname}`), only matches \"..\" that stands as a whole path segment, while the containment test is the string comparison pathname.startsWith(publicPathPathname) and the file path is built as path.join(outputPath, pathname.slice(publicPathPathname.length)). When the configured publicPath has no trailing slash, a request such as GET /assets../.env against publicPath /assets yields the pathname /assets../.env, whose only dot-dot sits inside the segment \"assets..\" and so passes the guard, but the offset slice cuts within that segment and hands \"../.env\" to path.join, resolving one directory above outputPath. Reading a file from that path requires the middleware to be backed by the physical filesystem, which happens when writeToDisk is true or a custom outputFileSystem is supplied, since the default memfs volume holds only build output. Traversal depth is limited to a single directory because a separately delimited dot-dot segment is collapsed during URL parsing before the guard runs. The default publicPath value of \"auto\" resolves to \"/\" and is not affected. This is an incomplete fix for CVE-2024-29180: the guard and offset slice were introduced by that fix and are present in every release from 5.3.4, 6.1.2 and 7.1.0 onward.",
"severity": [
"severity": [],
"affected": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N"
},
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
"package": {
"ecosystem": "npm",
"name": "webpack-dev-middleware"
},
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "7.1.0"
},
{
"fixed": "7.4.6"
}
]
}
]
}
],
"affected": [],
"references": [
{
"type": "ADVISORY",
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