CVE-2026-25150 is a critical-severity (CVSS 9.3) CWE-1321 vulnerability in @builder.io/qwik-city. A fix is available for @builder.io/qwik-city — see the affected versions and patch details below.
Prototype Pollution via FormData Processing in Qwik City
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-25150.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-25150 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@builder.io/qwik-citynpmDescription
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @builder.io/qwik-city | all versions | 1.19.0npm install @builder.io/qwik-city@1.19.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @builder.io/qwik-city, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @builder.io/qwik-city to 1.19.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-25150 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-25150 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-25150. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-25150 in your dependencies?
O3 Security finds CVE-2026-25150 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.