Is CVE-2026-9595 in the CISA KEV catalog?

No. CVE-2026-9595 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-9595?

CVE-2026-9595 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2026-9595?

CVE-2026-9595 has an EPSS score of 0.16% (6th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-9595?

Upgrade webpack-dev-server to 5.2.5 or later.

CVE & CISA-KEV Catalog

CVE-2026-9595

MEDIUM

5.3

CVSS v3

NVD

Description

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.

CWE-346 CWE-441

How to fix

Remediation Available

webpack-dev-serverNVD

Affected:< 5.2.5Fixed in:5.2.5CVE-2026-9595derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityLow

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Exploit Intelligence

0.16%probability of exploitation in 30 days

6thpercentile

Low risk: more likely to be exploited than 6% of all known CVEs.

References

Patch3

Vendor Advisory2

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-16.