CVE-2026-25150: Prototype Pollution via FormData Processing in Qwik City

Severity: critical (CVSS 10.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-03 · updated 2026-06-17
Weakness: CWE-1321

Description

Qwik is a performance focused javascript framework. Prior to version 1.19.0, a prototype pollution vulnerability exists in the formToObj() function within @builder.io/qwik-city middleware. The function processes form field names with dot notation (e.g., user.name) to create nested objects, but fails to sanitize dangerous property names like __proto__, constructor, and prototype. This allows unauthenticated attackers to pollute Object.prototype by sending crafted HTTP POST requests, potentially leading to privilege escalation, authentication bypass, or denial of service. This issue has been patched in version 1.19.0.

Affected products

QwikDev qwik: before 1.19.0 — fixed in 1.19.0

How to fix

Upgrade to a fixed version: QwikDev qwik 1.19.0. Check the vendor advisory for mitigations.

References

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