Vulnerability-Lookup

GHSA-79CF-XCQC-C78W

Vulnerability from github – Published: 2026-05-18 13:31 – Updated: 2026-05-18 13:31

Summary

webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins

Details

Impact

When webpack-dev-server is running on a non-HTTPS origin (the default), cross-origin requests from malicious websites can load the dev server's JavaScript bundles via <script> tags. The fix introduced in v5.2.1 (CVE-2025-30359) relied on Sec-Fetch-Mode and Sec-Fetch-Site request headers to block these requests, but browsers only send these headers for potentially trustworthy origins. Over plain HTTP, the headers are absent and the check is bypassed.

An attacker who knows the dev server's host, port, and output path can exfiltrate all module source code by intercepting the webpack runtime's module registration.

This does not affect Chrome 142+ (and other Chromium-based browsers) due to local network access restrictions.

Patches

Patched in webpack-dev-server >= 5.2.4 by setting Cross-Origin-Resource-Policy: same-origin on responses.

Workarounds

Run the dev server with HTTPS enabled (--https or server.type: 'https' in config).

Resources

GHSA-4v9v-hfq4-rm2v (CVE-2025-30359) - original vulnerability
GHSA-9jgg-88mc-972h (CVE-2025-30360) - prior bypass

Severity ?

5.3 (Medium)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 5.2.3"
      },
      "package": {
        "ecosystem": "npm",
        "name": "webpack-dev-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.2.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-6402"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-749"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-18T13:31:42Z",
    "nvd_published_at": "2026-05-12T09:16:55Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nWhen webpack-dev-server is running on a non-HTTPS origin (the default), cross-origin requests from malicious websites can load the dev server\u0027s JavaScript bundles via `\u003cscript\u003e` tags. The fix introduced in v5.2.1 (CVE-2025-30359) relied on `Sec-Fetch-Mode` and `Sec-Fetch-Site` request headers to block these requests, but browsers only send these headers for [potentially trustworthy origins](https://w3c.github.io/webappsec-secure-contexts/#is-origin-trustworthy). Over plain HTTP, the headers are absent and the check is bypassed.\n\nAn attacker who knows the dev server\u0027s host, port, and output path can exfiltrate all module source code by intercepting the webpack runtime\u0027s module registration.\n\nThis does not affect Chrome 142+ (and other Chromium-based browsers) due to [local network access restrictions](https://developer.chrome.com/release-notes/142#local_network_access_restrictions).\n\n### Patches\n\nPatched in webpack-dev-server \u003e= 5.2.4 by setting `Cross-Origin-Resource-Policy: same-origin` on responses.\n\n### Workarounds\n\nRun the dev server with HTTPS enabled (`--https` or `server.type: \u0027https\u0027` in config).\n\n### Resources\n\n- [GHSA-4v9v-hfq4-rm2v](https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-4v9v-hfq4-rm2v) (CVE-2025-30359) - original vulnerability\n- [GHSA-9jgg-88mc-972h](https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-9jgg-88mc-972h) (CVE-2025-30360) - prior bypass",
  "id": "GHSA-79cf-xcqc-c78w",
  "modified": "2026-05-18T13:31:42Z",
  "published": "2026-05-18T13:31:42Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-4v9v-hfq4-rm2v"
    },
    {
      "type": "WEB",
      "url": "https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-79cf-xcqc-c78w"
    },
    {
      "type": "WEB",
      "url": "https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-9jgg-88mc-972h"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6402"
    },
    {
      "type": "WEB",
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/webpack/webpack-dev-server"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins"
}

CVE-2026-6402 (GCVE-0-2026-6402)

Vulnerability from cvelistv5 – Published: 2026-05-12 07:45 – Updated: 2026-05-12 13:00

Title

webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins

Summary

webpack-dev-server versions up to and including 5.2.3 are vulnerable to cross-origin source code exposure when serving over a non-potentially trustworthy origin such as plain HTTP. The previous fix relied on the Sec-Fetch-Mode and Sec-Fetch-Site request headers, which browsers omit for non-trustworthy origins, allowing a malicious site to load the bundled source as a script and read it across origins. Impact: an attacker controlling a website visited by a developer running webpack-dev-server can recover the application source code when the dev server runs over HTTP at a guessable host and port. Chromium based browsers from Chrome 142 onward are not affected due to local network access restrictions. Upgrade to webpack-dev-server 5.2.4 or later, which sets Cross-Origin-Resource-Policy: same-origin on responses.

Severity ?

5.3 (Medium)


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

CWE

CWE-749 - Exposed Dangerous Method or Function

Assigner

openjs

References

2 references

URL	Tags
https://github.com/webpack/webpack-dev-server/sec…
https://cna.openjsf.org/security-advisories.html

Impacted products

1 product

Vendor	Product	Version
webpack-dev-server	webpack-dev-server	Affected: 0 , < 5.2.4 (semver) Unaffected: 5.2.4 (semver)

Credits

sapphi-red Ulises Gascón Sebastian Beltran Alexander Akait

Show details on NVD website

JSON

To clipboard

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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.

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