ZDF
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2026-6402

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.

Published May 12, 2026 · catalog updated Jun 17, 2026 · webpack-dev-server versions up to

Check if you run it

No confirmed exploitation is on record for CVE-2026-6402. EPSS is 0.35%. Act only if a listed version of webpack-dev-server versions up to is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (webpack-dev-server versions up to).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.35%
Remediation
Version ranges on file
Affected products
cpe webpack.js/webpack-dev-server · stated webpack-dev-server

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe webpack.js/webpack-dev-serverversion unspecified
  • stated webpack-dev-server<= 5.2.3

How to fix CVE-2026-6402

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-6402. EPSS is 0.35%. Act only if a listed version of webpack-dev-server versions up to is installed.

Which versions are affected?

Compare what you have installed with <= 5.2.3. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-749. EPSS 0.35%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 12, 2026 · NIST NVD

    Detected

    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 orig

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 orig

Sources

  • CVE.orgVulnerability recordCVE-2026-6402

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-6402

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2026-6402

    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 om

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.