CVE-2026-6402

MEDIUMNVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.3 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 88% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 5.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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 v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
24
EG Risk 24/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity53% × 45%
Exploitation0% × 40%
Automatability0% × 15%
EPSS PROB
0.4%
EPSS %ILE
26th
KEV
Not listed

Published

May 12, 2026

Last Modified

May 18, 2026

Advisory Details (2)

Auto-updated May 12, 2026
Patch available. Sources: github.
githubMentions a patch (unverified)

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

https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-79cf-xcqc-c78w
generic

Security Advisories | OpenJS Foundation CVE Numbering Authority

https://cna.openjsf.org/security-advisories.html

Vendor Advisories for CVE-2026-6402(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFix by version rangeDependents
webpack-dev-server—
  • every version up to 5.2.4: fixed in 5.2.4
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 25× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 176 total refreshes for this CVE.

  1. 2026-10-10 20:00 UTCEPSS rescore
  2. 2026-10-09 20:07 UTCEPSS rescore
  3. 2026-10-08 17:13 UTCEPSS rescore
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  24. 2026-09-11 11:23 UTCOSV refresh
  25. 2026-09-11 09:37 UTCEPSS rescore
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  1. 2026-09-08 22:01 UTCEPSS rescore
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  22. 2026-08-17 10:57 UTCEG score recompute
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  40. 2026-08-06 13:47 UTCEPSS rescore
  41. 2026-08-05 21:53 UTCEG score recompute
  42. 2026-08-05 19:17 UTCEPSS rescore
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  44. 2026-08-04 15:10 UTCEPSS rescore
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  46. 2026-08-04 04:23 UTCEG score recompute
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  50. 2026-08-02 00:06 UTCEG score recompute
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  64. 2026-07-23 03:22 UTCEG score recompute
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  67. 2026-07-21 15:25 UTCEPSS rescore
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  69. 2026-07-20 17:08 UTCEPSS rescore
  70. 2026-07-19 14:31 UTCEPSS rescore
  71. 2026-07-19 02:29 UTCEPSS rescore
  72. 2026-07-18 10:04 UTCEPSS rescore
  73. 2026-07-16 17:03 UTCEPSS rescore
  74. 2026-07-16 12:49 UTCOSV refresh
  75. 2026-07-15 16:57 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2026-6402?
CVE-2026-6402 is a medium vulnerability published on May 12, 2026. 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…
When was CVE-2026-6402 disclosed?
CVE-2026-6402 was first published on May 12, 2026, with the most recent update on May 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-6402 actively exploited?
CVE-2026-6402 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (26th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-6402?
CVE-2026-6402 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-6402?
A fix for CVE-2026-6402 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-6402 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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