# CVE-2026-81887

## Summary

- **CVE ID:** CVE-2026-81887
- **Severity:** MEDIUM
- **CVSS Score:** 5.1 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N)
- **CWE:** CWE-79, CWE-1321
- **Published:** Aug 31, 2026
- **Last Modified:** Sep 3, 2026

## Description

Livewire is a full-stack framework for Laravel. From 3.0.0-beta.1 until 3.8.3 and 4.3.4, the dot-notated query-string parser in js/plugins/history/index.js, including fromQueryString() and insertDotNotatedValueIntoData(), accepts the __proto__, constructor, and prototype path segments and creates inherited objects. Client-side state handlers then access effects.html, effects.js, effects.xjs, and effects.scripts without Object.prototype.hasOwnProperty.call(), allowing inherited attacker-controlled state to be treated as trusted effects. An unauthenticated attacker can craft a URL that, when opened by a user, executes arbitrary JavaScript in the affected application's origin. Exploitation requires user interaction and does not bypass server-side authorization or grant privileges beyond the affected user. This issue is fixed in versions 3.8.3 and 4.3.4.

## Affected Products

- livewire — livewire (>= 3.0.0-beta.1, < 3.8.3)
- livewire — livewire (>= 4.0.0-beta.1, < 4.3.4)

## References

- [CNA](https://github.com/livewire/livewire/security/advisories/GHSA-g3hc-697w-wm82)
- [CNA](https://github.com/livewire/livewire/pull/10467)
- [CNA](https://github.com/livewire/livewire/commit/11ebe646f7e81dde2d714815da8b3019d058561e)
- [CNA](https://github.com/livewire/livewire/releases/tag/v3.8.3)
- [CNA](https://github.com/livewire/livewire/releases/tag/v4.3.4)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.50%
- **EPSS Percentile:** 41.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._