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
5.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.3Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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
5.3(medium)
EPSS
12.0%
KEV
Not listed

Published

May 12, 2026

Last Modified

May 18, 2026

Advisory Details (2)

Auto-updated May 12, 2026
Patch available. Sources: github.
github Patch Available

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 rangeFixed inDependents
webpack-dev-server—5.2.4—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 50× 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.

  1. 2026-07-11 08:27 UTCEPSS rescore
  2. 2026-07-11 08:27 UTCEPSS rescore
  3. 2026-07-09 19:10 UTCEPSS rescore
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  5. 2026-07-08 15:16 UTCEPSS rescore
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  7. 2026-07-07 13:46 UTCEPSS rescore
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  9. 2026-07-06 16:27 UTCEPSS rescore
  10. 2026-07-06 16:27 UTCEPSS rescore
  11. 2026-07-06 02:23 UTCEPSS rescore
  12. 2026-07-06 02:23 UTCEPSS rescore
  13. 2026-07-05 02:31 UTCEPSS rescore
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  15. 2026-07-04 06:31 UTCEPSS rescore
  16. 2026-07-04 06:31 UTCEPSS rescore
  17. 2026-07-01 15:07 UTCEPSS rescore
  18. 2026-06-29 14:06 UTCEPSS rescore
  19. 2026-06-28 14:07 UTCEPSS rescore
  20. 2026-06-28 11:39 UTCEG score recompute
  21. 2026-06-28 04:56 UTCEPSS rescore
  22. 2026-06-27 08:38 UTCEG score recompute
  23. 2026-06-27 03:08 UTCEPSS rescore
  24. 2026-06-26 04:10 UTCEG score recompute
  25. 2026-06-25 13:50 UTCEPSS rescore
Show 64 more
  1. 2026-06-24 14:05 UTCEPSS rescore
  2. 2026-06-23 21:33 UTCEPSS rescore
  3. 2026-06-23 21:33 UTCEPSS rescore
  4. 2026-06-22 14:25 UTCEPSS rescore
  5. 2026-06-22 14:25 UTCEPSS rescore
  6. 2026-06-21 14:56 UTCEPSS rescore
  7. 2026-06-21 14:56 UTCEPSS rescore
  8. 2026-06-21 01:59 UTCEPSS rescore
  9. 2026-06-21 01:59 UTCEPSS rescore
  10. 2026-06-19 19:26 UTCEPSS rescore
  11. 2026-06-19 19:26 UTCEPSS rescore
  12. 2026-06-18 17:52 UTCEPSS rescore
  13. 2026-06-18 17:52 UTCEPSS rescore
  14. 2026-06-17 17:53 UTCEPSS rescore
  15. 2026-06-16 17:53 UTCEPSS rescore
  16. 2026-06-16 06:56 UTCEG score recompute
  17. 2026-06-15 17:49 UTCEPSS rescore
  18. 2026-06-15 17:49 UTCEPSS rescore
  19. 2026-06-14 23:18 UTCEPSS rescore
  20. 2026-06-14 09:11 UTCEG score recompute
  21. 2026-06-13 23:00 UTCEPSS rescore
  22. 2026-06-13 06:58 UTCEG score recompute
  23. 2026-06-12 23:12 UTCEPSS rescore
  24. 2026-06-12 23:12 UTCEPSS rescore
  25. 2026-06-12 04:15 UTCEG score recompute
  26. 2026-06-11 14:00 UTCEPSS rescore
  27. 2026-06-11 02:03 UTCEG score recompute
  28. 2026-06-10 22:19 UTCEPSS rescore
  29. 2026-06-10 13:22 UTCEPSS rescore
  30. 2026-06-09 23:54 UTCEG score recompute
  31. 2026-06-08 21:46 UTCEG score recompute
  32. 2026-06-08 14:17 UTCEPSS rescore
  33. 2026-06-07 19:37 UTCEG score recompute
  34. 2026-06-07 15:25 UTCEPSS rescore
  35. 2026-06-06 17:29 UTCEG score recompute
  36. 2026-06-06 13:47 UTCEPSS rescore
  37. 2026-06-05 22:47 UTCEPSS rescore
  38. 2026-06-05 15:20 UTCEG score recompute
  39. 2026-06-05 06:10 UTCEPSS rescore
  40. 2026-06-04 13:12 UTCEPSS rescore
  41. 2026-06-04 13:11 UTCEG score recompute
  42. 2026-06-03 11:02 UTCEG score recompute
  43. 2026-06-02 20:13 UTCEPSS rescore
  44. 2026-06-02 08:53 UTCEG score recompute
  45. 2026-06-01 13:52 UTCEPSS rescore
  46. 2026-06-01 13:52 UTCEPSS rescore
  47. 2026-06-01 06:44 UTCEG score recompute
  48. 2026-05-31 22:30 UTCEPSS rescore
  49. 2026-05-31 22:30 UTCEPSS rescore
  50. 2026-05-31 00:16 UTCEPSS rescore
  51. 2026-05-31 00:16 UTCEPSS rescore
  52. 2026-05-29 13:44 UTCEPSS rescore
  53. 2026-05-29 13:44 UTCEPSS rescore
  54. 2026-05-28 13:44 UTCEPSS rescore
  55. 2026-05-28 13:44 UTCEPSS rescore
  56. 2026-05-27 13:40 UTCEPSS rescore
  57. 2026-05-27 13:40 UTCEPSS rescore
  58. 2026-05-26 13:44 UTCEPSS rescore
  59. 2026-05-26 07:18 UTCEPSS rescore
  60. 2026-05-23 00:07 UTCEG score recompute
  61. 2026-05-21 22:43 UTCEPSS rescore
  62. 2026-05-20 22:38 UTCEPSS rescore
  63. 2026-05-20 13:02 UTCEG score recompute
  64. 2026-05-20 11:22 UTCEPSS rescore

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 in the National Vulnerability Database 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 12.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
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?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-6402, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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