Description
In versions before 20.0.2, it was found that --disallow-code-generation-from-strings is not sufficient for isolating untrusted JavaScript in happy-dom. The untrusted script and the rest of the application still run in the same Isolate/process, so attackers can deploy prototype pollution payloads to hijack important references like "process" in the example below, or to hijack control flow via flipping checks of undefined property. This vulnerability is due to an incomplete fix for CVE-2025-61927. The vulnerability is fixed in 20.0.2.
Scores
CVSS v4
9.4
EPSS
0.0014
EPSS Percentile
34.2%
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
no
Technical Impact
total
Details
CWE
CWE-1321
Status
published
Products (2)
capricorn86/happy-dom
< 20.0.2
npm/happy-dom
19.0.0 - 20.0.2npm
Published
Oct 15, 2025
Tracked Since
Feb 18, 2026