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webpack-dev-middleware vulnerable to Path Traversal via non-slash-terminated publicPath

Type: advisorySource: OSV1 source record

> [!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

Announced Source revision 1
Original source ↗

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

Linked CVE context

These ratings describe the referenced vulnerabilities and products. They are not a severity rating for every application using this dependency.

CVE-2026-76844 · High

zlib

Event
#72823 · Revision 1
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Publisher date
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