GHSA-G84C-RXFJ-3J2C
Vulnerability from github – Published: 2026-09-29 16:59 – Updated: 2026-09-29 16:59[!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 a trailing slash (for example /assets/ instead of /assets), or upgrade to a patched version.
References
- CVE-2024-29180 (GHSA-wr3j-pwj9-hqq6), the earlier path traversal in the same component that this issue bypasses.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "webpack-dev-middleware"
},
"ranges": [
{
"events": [
{
"introduced": "8.0.0"
},
{
"fixed": "8.3.0"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c 7.4.5"
},
"package": {
"ecosystem": "npm",
"name": "webpack-dev-middleware"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "7.4.6"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-76844"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-29T16:59:18Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "\u003e [!IMPORTANT]\n\u003e 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.\n\n### Impact\n\n`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.\n\n### Patches\n\nPatched 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.\n\n### Workarounds\n\nConfigure `publicPath` with a trailing slash (for example `/assets/` instead of `/assets`), or upgrade to a patched version.\n\n### References\n\n- [CVE-2024-29180](https://www.cve.org/CVERecord?id=CVE-2024-29180) ([GHSA-wr3j-pwj9-hqq6](https://github.com/webpack/webpack-dev-middleware/security/advisories/GHSA-wr3j-pwj9-hqq6)), the earlier path traversal in the same component that this issue bypasses.",
"id": "GHSA-g84c-rxfj-3j2c",
"modified": "2026-09-29T16:59:18Z",
"published": "2026-09-29T16:59:18Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/webpack/webpack-dev-middleware/security/advisories/GHSA-g84c-rxfj-3j2c"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-76844"
},
{
"type": "WEB",
"url": "https://github.com/webpack/webpack-dev-middleware/pull/2404"
},
{
"type": "WEB",
"url": "https://github.com/webpack/webpack-dev-middleware/commit/13344e78b26d88fe9b7c8381a3860e248a52359b"
},
{
"type": "WEB",
"url": "https://github.com/webpack/webpack-dev-middleware/commit/cefccbac330c29052fc6dffe85fd292ea2ac782b"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-wr3j-pwj9-hqq6"
},
{
"type": "PACKAGE",
"url": "https://github.com/webpack/webpack-dev-middleware"
},
{
"type": "WEB",
"url": "https://github.com/webpack/webpack-dev-middleware/blob/v8.1.1/src/middleware.js"
},
{
"type": "WEB",
"url": "https://github.com/webpack/webpack-dev-middleware/releases/tag/v7.4.6"
},
{
"type": "WEB",
"url": "https://github.com/webpack/webpack-dev-middleware/releases/tag/v8.3.0"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/webpack-dev-middleware-path-traversal-via-offset-slice-on-a-non-slash-terminated-publicpath"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "webpack-dev-middleware vulnerable to Path Traversal via non-slash-terminated publicPath"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.