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CVE-2026-6402VulnerabilityPublished Updated

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

Affects MicrosoftSource GCVE Database

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Not known to be exploited.

Data as of 30 Oct 2026, 11:52 UTC

Severity
Medium

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS
0.2% chance of exploitation in 30 days – higher than 21% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 2 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Microsoft Security Response Center MicrosoftAffected
  • =3.0
  • Microsoft
  • Azure Linux
  • 3.0
  • Azure Linux 3.0
  • azl3 python-tensorboard 0:2.16.2-6.azl3
Fixed in–

AI-suggested

Until a patch is available, users should avoid running webpack-dev-server on non-HTTPS origins to prevent source code exposure. Using HTTPS for development servers or restricting access to trusted networks may reduce risk.

Description

CVE-2026-6402 is a vulnerability affecting webpack-dev-server when used on non-HTTPS origins, leading to cross-origin source code exposure. The vulnerability is categorized under CWE-749, which relates to the improper protection of sensitive information. The affected products include Microsoft and Azure Linux versions 3.0. There is no CVSS score provided, and no known exploits in the wild have been reported. No patch or remediation information is currently available from the vendor advisory. The vulnerability could allow unauthorized access to source code when the server is accessed over non-secure (non-HTTPS) connections.

References

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