Is CVE-2026-34226 in the CISA KEV catalog?

No. CVE-2026-34226 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-34226?

CVE-2026-34226 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2026-34226?

CVE-2026-34226 has an EPSS score of 0.46% (37th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-34226?

Upgrade happy dom to 20.8.9 or later.

CVE & CISA-KEV Catalog

CVE-2026-34226

HIGH

7.5

CVSS v3

NVD

Description

Happy DOM is a JavaScript implementation of a web browser without its graphical user interface. Versions prior to 20.8.9 may attach cookies from the current page origin (`window.location`) instead of the request target URL when `fetch(..., { credentials: "include" })` is used. This can leak cookies from origin A to destination B. Version 20.8.9 fixes the issue.

CWE-201 CWE-359

How to fix

Remediation Available

happy domNVD

Affected:< 20.8.9Fixed in:20.8.9CVE-2026-34226derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

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

ConfidentialityHigh

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

0.46%probability of exploitation in 30 days

37thpercentile

Low risk: more likely to be exploited than 37% of all known CVEs.

References

Patch3

Exploit1

github.com

Release Notes1

github.com

Other references3

Related Vulnerabilities

Other CWE-201 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-60188	High	7.5	2.9%	-	-
CVE-2017-16026	Medium	5.9	2.6%	-	Fix
CVE-2017-2582	Medium	6.5	2.5%	-	Fix
CVE-2022-27779	Medium	5.3	2.4%	-	Fix
CVE-2020-26085	Critical	9.9	2.2%	-	Fix
CVE-2024-32825	High	7.5	2.0%	-	-

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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 2026-07-15.