CVE-2026-84994 Qwik - Denial of Service

Qwik prior to @builder.io/qwik 1.20.0 and @qwik.dev/core 2.0.0-beta.37 contains a denial of service caused by improper handling of attacker-controlled thenables in server-side qwik-json deserialization, letting unauthenticated attackers crash Node.js servers, exploit requires sending crafted unauthenticated requests.

CVSS base score 8.7 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.52% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Denial of Service
Impact
Denial Of Service
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published
13 October 2026
Updated
15 October 2026
Weakness
CWE-248

Vendor fix

Update to @builder.io/qwik 1.20.0 and @qwik.dev/core 2.0.0-beta.37 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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