Livewire DOM-based cross-site scripting during client-side state handling (CVE-2026-81887) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-81887

Livewire DOM-based cross-site scripting during client-side state handling

Answer in brief

CVE-2026-81887 records a Unknown severity vulnerability in Livewire DOM-based cross-site scripting during client-side state handling. The current sources do not mark it as known exploited. The current feed maps livewire/livewire (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 31, 2026Updated Aug 31, 2026Source checked Aug 31, 2026First seen by HOL Aug 31, 2026Material review Aug 31, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps livewire/livewire (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
livewire/livewiregeneric	>= 3.0.0-beta.1, < 3.8.3 \|\| >= 4.0.0-beta.1, < 4.3.4	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for livewire/livewire.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 31, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 31, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 31, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.