CVE-2026-6402
MediumWhat is 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. 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.
CVSS Vector Breakdown
CVSS 3.1Exploitable remotely over the network without requiring access to the local system.
Exploit requires specific conditions, timing, or configuration to succeed.
No authentication required. Any anonymous user can exploit this vulnerability.
Victim must take an action (e.g. click a link, open a file) for the exploit to succeed.
Exploiting the vulnerability only affects the vulnerable component itself.
Complete loss of confidentiality. All data on the component may be exposed.
No integrity impact. Data cannot be modified.
No availability impact. Service remains fully operational.
FAQ
CVE-2026-6402 has a CVSS score of 5.3/10, rated as Medium. Review the affected products list and apply vendor patches.
CVSS (Common Vulnerability Scoring System) rates vulnerability severity from 0.0 to 10.0. CVE-2026-6402 scores 5.3/10 (Medium). Scores 9.0–10.0 are Critical, 7.0–8.9 are High, 4.0–6.9 are Medium, and below 4.0 are Low.
The list of devices confirmed to be affected by CVE-2026-6402 is shown in the "Affected Devices" section above. Check your firmware version against the vendor security advisory and apply the latest patch.
Apply the latest firmware or software update from the vendor. Check the References section above for official advisories and patch notes. If no patch is available, consider disabling the affected feature or isolating the device from untrusted networks.