webpack-dev-middleware vulnerable to Path Traversal via non-slash-terminated publicPath
> [!IMPORTANT] > CVE-2026-76844 was assigned and published for this issue by VulnCheck on 2026-08-24 without prior coordination with the webpack maintainers or the OpenJS Foundation, which holds the CVE Numbering Authority scope for webpack projects. Neither the maintainers nor the OpenJS CNA were notified before publication, and no fix was available at that time. This advisory is the coordinated record produced by the webpack maintainers and the OpenJS Foundation CNA. ### Impact `webpack-dev-middleware` resolves a request to a local file in `getFilenameFromUrl`. When the configured `publicPath` has no trailing slash (for example `/assets`), a request that shares that prefix without being under it (for example `/assets../secret`) still passes the containment check, and the `..` guard does not catch it because it runs on the path before the `publicPath` prefix is stripped. The stripped remainder then escapes the configured output directory once joined, so an unauthenticated request can read files outside the output root. Applications serving `webpack-dev-middleware` (directly or via `webpack-dev-server`) with a `publicPath` that does not end in a slash are affected. A development server reachable on the network can be attacked with a single request and no victim interaction. ### Patches Patched in `webpack-dev-middleware` 8.3.0. There is no backport to the 5.x, 6.x, or 7.x lines; users on those lines should upgrade to 8.3.0 or later. ### Workarounds Configure `publicPath` with
GHSA-g84c-rxfj-3j2c
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:GHSA-g84c-rxfj-3j2c
webpack-dev-middleware
Source reference: /affected/0/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 8.3.0
Source reference:
/affected/0/ranges - Prerequisites
- Not stated in this record
webpack-dev-middleware
Source reference: /affected/1/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 7.4.6
Source reference:
/affected/1/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "SEMVER",
"events": [
{
"introduced": "8.0.0"
},
{
"fixed": "8.3.0"
}
]
}
],
"package": {
"name": "webpack-dev-middleware",
"purl": "pkg:npm/webpack-dev-middleware",
"ecosystem": "npm"
},
"database_specific": {
"source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-g84c-rxfj-3j2c/GHSA-g84c-rxfj-3j2c.json"
}
},
{
"ranges": [
{
"type": "SEMVER",
"events": [
{
"introduced": "0"
},
{
"fixed": "7.4.6"
}
]
}
],
"package": {
"name": "webpack-dev-middleware",
"purl": "pkg:npm/webpack-dev-middleware",
"ecosystem": "npm"
},
"database_specific": {
"source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-g84c-rxfj-3j2c/GHSA-g84c-rxfj-3j2c.json",
"last_known_affected_version_range": "< 7.4.5"
}
}
]- Related CVEs
- CVE-2026-76844
Source reference:
/aliases
Publisher severity
high
Source reference: /database_specific/severity
- Event
- #72823 · Revision 1
- Added to Heist Feed
- Publisher date