Vulnerability-Lookup

GHSA-P3F5-W63M-MXPH

Vulnerability from github – Published: 2026-08-24 15:31 – Updated: 2026-08-24 15:31

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

7.4 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N

8.3 (High)


                  
                    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

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JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-76844"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-24T14:17:02Z",
    "severity": "HIGH"
  },
  "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.",
  "id": "GHSA-p3f5-w63m-mxph",
  "modified": "2026-08-24T15:31:51Z",
  "published": "2026-08-24T15:31:51Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-76844"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-wr3j-pwj9-hqq6"
    },
    {
      "type": "WEB",
      "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://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"
    },
    {
      "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",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-76844 (GCVE-0-2026-76844)

Vulnerability from cvelistv5 – Published: 2026-08-24 13:12 – Updated: 2026-08-24 13:12

Title

webpack-dev-middleware Path Traversal via Offset Slice on a Non-Slash-Terminated publicPath

Summary

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

8.3 (High)


                        
                          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

7.4 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N

CWE

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Assigner

VulnCheck mitre root

References

4 references

URL	Tags
https://github.com/webpack/webpack-dev-middleware	product
https://github.com/webpack/webpack-dev-middleware…	technical-description
https://github.com/advisories/GHSA-wr3j-pwj9-hqq6	related
https://www.vulncheck.com/advisories/webpack-dev-…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
webpack	webpack-dev-middleware	Affected: 5.3.4 , ≤ 5.3.4 (semver) Affected: 6.1.2 , ≤ 6.1.3 (semver) Affected: 7.1.0 , ≤ 7.4.5 (semver) Affected: 8.0.0 , ≤ 8.1.1 (semver) cpe:2.3:a:webpack.js:webpack-dev-middleware:::::::: cpe:2.3:a:webpack.js:webpack-dev-middleware:::::::: cpe:2.3:a:webpack.js:webpack-dev-middleware:::::::: cpe:2.3:a:webpack.js:webpack-dev-middleware::::::::

Date Public

2026-08-20 00:00

Credits

Muhammad Sobirov

Show details on NVD website

JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://www.npmjs.com/package/webpack-dev-middleware",
          "defaultStatus": "unaffected",
          "packageName": "webpack-dev-middleware",
          "packageURL": "pkg:npm/webpack-dev-middleware",
          "product": "webpack-dev-middleware",
          "vendor": "webpack",
          "versions": [
            {
              "lessThanOrEqual": "5.3.4",
              "status": "affected",
              "version": "5.3.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.3",
              "status": "affected",
              "version": "6.1.2",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.4.5",
              "status": "affected",
              "version": "7.1.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "8.1.1",
              "status": "affected",
              "version": "8.0.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:webpack.js:webpack-dev-middleware:*:*:*:*:*:*:*:*",
                  "versionEndIncluding": "5.3.4",
                  "versionStartIncluding": "5.3.4",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:a:webpack.js:webpack-dev-middleware:*:*:*:*:*:*:*:*",
                  "versionEndIncluding": "6.1.3",
                  "versionStartIncluding": "6.1.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:a:webpack.js:webpack-dev-middleware:*:*:*:*:*:*:*:*",
                  "versionEndIncluding": "7.4.5",
                  "versionStartIncluding": "7.1.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:a:webpack.js:webpack-dev-middleware:*:*:*:*:*:*:*:*",
                  "versionEndIncluding": "8.1.1",
                  "versionStartIncluding": "8.0.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Muhammad Sobirov"
        }
      ],
      "datePublic": "2026-08-20T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.3,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "HIGH",
            "subIntegrityImpact": "NONE",
            "userInteraction": "PASSIVE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "NONE"
          },
          "format": "CVSS"
        },
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 7.4,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "REQUIRED",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N",
            "version": "3.1"
          },
          "format": "CVSS"
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-22",
              "description": "Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-24T13:12:01.148Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
      },
      "references": [
        {
          "tags": [
            "product"
          ],
          "url": "https://github.com/webpack/webpack-dev-middleware"
        },
        {
          "tags": [
            "technical-description"
          ],
          "url": "https://github.com/webpack/webpack-dev-middleware/blob/v8.1.1/src/middleware.js"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://github.com/advisories/GHSA-wr3j-pwj9-hqq6"
        },
        {
          "name": "VulnCheck Advisory: webpack-dev-middleware Path Traversal via Offset Slice on a Non-Slash-Terminated publicPath",
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/webpack-dev-middleware-path-traversal-via-offset-slice-on-a-non-slash-terminated-publicpath"
        }
      ],
      "title": "webpack-dev-middleware Path Traversal via Offset Slice on a Non-Slash-Terminated publicPath",
      "x_generator": {
        "engine": "vulncheck-endgame"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-76844",
    "datePublished": "2026-08-24T13:12:01.148Z",
    "dateReserved": "2026-08-19T20:34:19.724Z",
    "dateUpdated": "2026-08-24T13:12:01.148Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
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.

Action not permitted

GHSA-P3F5-W63M-MXPH

CVE-2026-76844 (GCVE-0-2026-76844)

Tags

Sightings

Nomenclature