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CVE-2026-25150

Prototype Pollution via FormData Processing in Qwik City

9.3 CriticalFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
High
Availability
Low

Exploit likelihood

0.72%Up 0.7 points since Feb 4, 2026
90%50%10%1%

What each source reports

CVE List Score used 9.3

Prototype Pollution via FormData Processing in Qwik City

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.

Record
CVE-2026-25150
CVSS 3.1
9.3 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
Weakness
CWE-1321
Updated
2026-11-02
EUVDEUVD-2026-5165 9.3

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.

Record
EUVD-2026-5165
CVSS 3.1
9.3 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
Updated
2026-11-02
GitHub AdvisoriesGHSA-xqg6-98cw-gxhq 9.3

Prototype Pollution via FormData Processing in Qwik City

Summary

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.

Impact

An unauthenticated attacker can supply specially crafted form field names that cause formToObj() to write dangerous keys (for example proto, constructor, prototype) into parsed objects. This results in Prototype Pollution of the server process and can cause privilege escalation, auth bypass, denial-of-service, or other global application integrity failures depending on how objects are used.

Record
GHSA-xqg6-98cw-gxhq
CVSS 3.1
9.3 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
Weakness
CWE-1321
Updated
2026-11-02
NVD 9.3

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.

Record
CVE-2026-25150
CVSS 3.1
9.3 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
CVSS 3.1
10.0 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Weakness
CWE-1321
Updated
2026-11-02
OSV 9.3

Prototype Pollution via FormData Processing in Qwik City

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.

Record
CVE-2026-25150
CVSS 3.1
9.3 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
Weakness
CWE-1321
Updated
2026-11-02
OSVGHSA-xqg6-98cw-gxhq 9.3

Prototype Pollution via FormData Processing in Qwik City

Summary

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.

Impact

An unauthenticated attacker can supply specially crafted form field names that cause formToObj() to write dangerous keys (for example proto, constructor, prototype) into parsed objects. This results in Prototype Pollution of the server process and can cause privilege escalation, auth bypass, denial-of-service, or other global application integrity failures depending on how objects are used.

Record
GHSA-xqg6-98cw-gxhq
CVSS 3.1
9.3 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
Weakness
CWE-1321
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
@builder.io/qwik-city
npm
before 1.19.0
1.19.0

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-25150 is a critical vulnerability (CVSS 9.3) in Qwik, published February 3, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.72%, the 54th percentile. Fixed in @builder.io/qwik-city 1.19.0.

References

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