CVE-2026-9595

MEDIUMNVD 4.34.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.3 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 94% 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
Trending — 3 sources updated this week
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.3Exploit: None knownExposed: 0

A fix is available — apply it.

Impact: When a user-configured proxy on webpack-dev-server has a broad context (e.g. /) and ws: true, it also intercepts the dev server's own HMR WebSocket and forwards it to the proxy target. This leaks the browser's cookies and Origin header to the backend, bypasses the dev server's Host/Origin validation, and corrupts the HMR socket (both HMR and the proxy end up writing to the same socket).

Patches: Fixed in [email protected].

Workarounds: Scope user-defined proxy context to specific paths instead of /, or omit ws: true from the proxy entry when WebSocket forwarding is not required.

CVSS v3
4.3
EG Score
4.3(medium)
EG Risk
24(Track)
EG Risk 24/100SSVC: Track

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
Severity43% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
6%
KEV
Not listed

Published

June 15, 2026

Last Modified

June 16, 2026

Advisory Details (5)

Auto-updated Jun 15, 2026
Patch available. Sources: github_pr, github_commit, github.
github Patch Available

webpack-dev-server vulnerable to HMR WebSocket interception via permissive user proxies · Advisory · webpack/webpack-dev-server · GitHub

https://github.com/webpack/webpack-dev-server/security/advisories/GHSA-mx8g-39q3-5c79
github_pr Patch Available

fix: skip HMR websocket path when forwarding upgrades to user-defined proxies

Patch available: webpack/webpack-dev-server v5.2.5 (PR #4316 merged 2026-05-25)

https://github.com/webpack/webpack-dev-server/pull/4316
github_commit Patch Available

commit 72ba7505aff2 (vuejs/vue-cli)

Patch available: vuejs/vue-cli v4.5.12 (contains commit 72ba7505aff2)

https://github.com/vuejs/vue-cli/commit/72ba7505aff2a8314e82aa5082379a77504a1fcb
github_pr Patch Available

Fix for #6720: HMR not working in Firefox if proxy option present

Patch available: facebook/create-react-app v3.1.0 (PR #7444 merged 2019-08-07)

https://github.com/facebook/create-react-app/pull/7444
generic

Security Advisories | OpenJS Foundation CVE Numbering Authority

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

Vendor Advisories for CVE-2026-9595(18)

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

Patch Availability(15)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatwebpack-dev-server2026-09-10redhat
redhatopenshift4/ose-console-rhel9:17870895232026-08-26redhat
redhatansible-automation-platform-26/gateway-rhel9:17872197512026-08-24redhat
redhatansible-automation-platform-27/gateway-rhel9:17872184092026-08-24redhat
redhatrh-podman-desktop-0:1.1.2-1.el10_22026-08-20redhat
redhatansible-automation-platform/automation-portal:17870471882026-08-18redhat
redhatansible-automation-platform/automation-portal:17870471142026-08-18redhat
redhatdiscovery/discovery-ui-rhel9:17866348252026-08-13redhat
redhatopenshift4/ose-agent-installer-ui-rhel9:17859108962026-08-11redhat
redhatansible-automation-platform-26/lightspeed-rhel9:17857753602026-08-04redhat
redhatansible-automation-platform-25/lightspeed-rhel8:17854301742026-08-04redhat
redhatrhmtc/openshift-migration-ui-rhel8:17836905322026-07-20redhat
redhatopenshift4/ose-console-rhel9:17835023382026-07-14redhat
redhatopenshift4/ose-console-rhel9:17836023262026-07-14redhat
redhatopenshift4/ose-console-rhel9:17829136212026-07-07redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
webpack-dev-server—5.2.5—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 38× 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 159 total refreshes for this CVE.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-17 19:32 UTCEPSS rescore
  3. 2026-09-16 14:09 UTCEPSS rescore
  4. 2026-09-16 05:15 UTCEPSS rescore
  5. 2026-09-15 03:12 UTCEPSS rescore
  6. 2026-09-14 03:47 UTCEG score recompute
  7. 2026-09-14 03:47 UTCVendor advisory
  8. 2026-09-13 16:48 UTCEPSS rescore
  9. 2026-09-12 15:02 UTCEPSS rescore
  10. 2026-09-11 09:38 UTCEPSS rescore
  11. 2026-09-10 09:35 UTCEPSS rescore
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  18. 2026-09-01 04:40 UTCEPSS rescore
  19. 2026-08-30 22:59 UTCEG score recompute
  20. 2026-08-30 22:59 UTCVendor advisory
  21. 2026-08-30 19:18 UTCEPSS rescore
  22. 2026-08-30 01:22 UTCEPSS rescore
  23. 2026-08-28 21:42 UTCEPSS rescore
  24. 2026-08-27 14:25 UTCEPSS rescore
  25. 2026-08-26 14:47 UTCEPSS rescore
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  1. 2026-08-25 13:49 UTCEPSS rescore
  2. 2026-08-24 23:38 UTCEG score recompute
  3. 2026-08-24 23:38 UTCVendor advisory
  4. 2026-08-24 14:18 UTCEPSS rescore
  5. 2026-08-23 09:49 UTCEG score recompute
  6. 2026-08-23 09:49 UTCVendor advisory
  7. 2026-08-23 00:19 UTCEPSS rescore
  8. 2026-08-21 23:49 UTCEPSS rescore
  9. 2026-08-21 09:54 UTCEG score recompute
  10. 2026-08-21 09:54 UTCVendor advisory
  11. 2026-08-20 22:56 UTCEPSS rescore
  12. 2026-08-20 11:29 UTCEG score recompute
  13. 2026-08-20 11:29 UTCVendor advisory
  14. 2026-08-19 17:04 UTCEPSS rescore
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  16. 2026-08-19 13:15 UTCVendor advisory
  17. 2026-08-18 13:49 UTCEPSS rescore
  18. 2026-08-17 13:47 UTCEPSS rescore
  19. 2026-08-16 22:35 UTCEG score recompute
  20. 2026-08-16 22:35 UTCVendor advisory
  21. 2026-08-16 14:56 UTCEPSS rescore
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  23. 2026-08-16 00:22 UTCVendor advisory
  24. 2026-08-15 02:08 UTCEG score recompute
  25. 2026-08-15 02:08 UTCVendor advisory
  26. 2026-08-15 01:31 UTCEPSS rescore
  27. 2026-08-14 03:55 UTCEG score recompute
  28. 2026-08-14 03:55 UTCVendor advisory
  29. 2026-08-13 22:00 UTCEPSS rescore
  30. 2026-08-13 05:42 UTCEG score recompute
  31. 2026-08-13 05:42 UTCVendor advisory
  32. 2026-08-12 13:51 UTCEPSS rescore
  33. 2026-08-12 07:29 UTCEG score recompute
  34. 2026-08-12 07:29 UTCVendor advisory
  35. 2026-08-11 13:43 UTCEPSS rescore
  36. 2026-08-11 09:03 UTCEG score recompute
  37. 2026-08-11 09:03 UTCVendor advisory
  38. 2026-08-11 00:00 UTCEPSS rescore
  39. 2026-08-10 10:50 UTCEG score recompute
  40. 2026-08-10 10:50 UTCVendor advisory
  41. 2026-08-09 13:47 UTCEPSS rescore
  42. 2026-08-09 12:37 UTCEG score recompute
  43. 2026-08-09 12:37 UTCVendor advisory
  44. 2026-08-08 16:37 UTCEPSS rescore
  45. 2026-08-08 14:24 UTCEG score recompute
  46. 2026-08-08 14:24 UTCVendor advisory
  47. 2026-08-07 16:30 UTCEPSS rescore
  48. 2026-08-07 16:11 UTCVendor advisory
  49. 2026-08-06 17:58 UTCEG score recompute
  50. 2026-08-06 17:58 UTCVendor advisory
  51. 2026-08-06 13:47 UTCEPSS rescore
  52. 2026-08-05 19:45 UTCEG score recompute
  53. 2026-08-05 19:45 UTCVendor advisory
  54. 2026-08-05 19:17 UTCEPSS rescore
  55. 2026-08-04 15:42 UTCEG score recompute
  56. 2026-08-04 15:42 UTCVendor advisory
  57. 2026-08-04 15:10 UTCEPSS rescore
  58. 2026-08-04 10:39 UTCEPSS rescore
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  60. 2026-08-03 08:58 UTCVendor advisory
  61. 2026-08-02 07:07 UTCEG score recompute
  62. 2026-08-02 07:07 UTCVendor advisory
  63. 2026-08-02 02:27 UTCEPSS rescore
  64. 2026-08-01 08:53 UTCEG score recompute
  65. 2026-08-01 08:53 UTCVendor advisory
  66. 2026-08-01 04:16 UTCEPSS rescore
  67. 2026-07-31 04:31 UTCEG score recompute
  68. 2026-07-31 04:31 UTCVendor advisory
  69. 2026-07-30 16:28 UTCEPSS rescore
  70. 2026-07-30 05:13 UTCEG score recompute
  71. 2026-07-30 05:13 UTCVendor advisory
  72. 2026-07-30 01:30 UTCEPSS rescore
  73. 2026-07-29 03:38 UTCEG score recompute
  74. 2026-07-29 03:38 UTCVendor advisory
  75. 2026-07-28 15:37 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-9595?
CVE-2026-9595 is a medium vulnerability published on June 15, 2026. Impact: When a user-configured proxy on webpack-dev-server has a broad context (e.g. /) and ws: true, it also intercepts the dev server's own HMR WebSocket and forwards it to the proxy target. This leaks the browser's cookies and Origin header to the backend, bypasses the dev server's Host/Origin…
When was CVE-2026-9595 disclosed?
CVE-2026-9595 was first published in the National Vulnerability Database on June 15, 2026, with the most recent update on June 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-9595 actively exploited?
CVE-2026-9595 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 94.1% of all scored CVEs.
What is the CVSS score of CVE-2026-9595?
CVE-2026-9595 has a CVSS v3 base score of 4.3 (NVD).
How do I remediate CVE-2026-9595?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-9595, 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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