livewire/livewire security advisory

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

CVE-2026-81887 is a medium-severity DOM-based XSS vulnerability in the PHP package livewire/livewire (CVSS 5.1), published 31 August 2026. The advisory does not name a fixed version. It can be exploited without an account.

medium 5.1 published 2026-08-31 · updated 2026-09-09

Affected versions: >= 3.0.0-beta.1, <= 3.8.2
>= 4.0.0-beta.1, <= 4.3.3
Fixed in: not stated
Newest release: 4.4.8
Severity: Medium · CVSS 5.1
Type: DOM-based cross-site scripting (XSS)
CWE-79, CWE-1321
Exploited in the wild: Not on the CISA KEV list
checked 2026-11-04

Is your livewire/livewire version affected?

Run composer show livewire/livewire in your project, then enter the version. We check it against this and every other known livewire/livewire advisory.

Who can exploit CVE-2026-81887

Access: No account. Anyone who can send a request to an app that uses the affected code.
Interaction: A user also has to do something, such as open a link or a page the attacker prepared.

CVSS vector (scored by GitHub): 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

Your app is only exposed if it uses the affected part of livewire/livewire. The advisory below says which part that is. If you are not sure, upgrade anyway: it costs less than finding out.

How to fix CVE-2026-81887 in livewire/livewire

Find the installed version: composer show livewire/livewire. If you never required it yourself, composer why livewire/livewire shows which package pulls it in.
Update it: composer update livewire/livewire --with-all-dependencies.
If Composer will not go that high, your composer.json constraint is holding it back. Widen it (for example "livewire/livewire": "^4.4.8" if you can take that version), or upgrade the package that requires it.
Run composer audit. It reads the same advisory data and should no longer list CVE-2026-81887.
Commit composer.lock and deploy it. On the server, run composer install --no-dev from the lock file, not composer update.

If you cannot upgrade yet

General hardening for DOM-based XSS issues while the upgrade waits. None of it replaces the fix.

Escape output in your own templates and add a Content-Security-Policy that blocks inline scripts.
Limit who can save the content the advisory names (for example rich text, SVG or form fields).
If your app does not use the affected feature, note that in your audit, but still plan the upgrade.

The CVE-2026-81887 advisory

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.

Description from the CVE record, published by GitHub (the CVE Numbering Authority), via the NVD entry for CVE-2026-81887. Advisory title: “Livewire DOM-based cross-site scripting during client-side state handling”.

References

GitHub advisory GHSA-g3hc-697w-wm82 github.com
Fix commit 11ebe64 github.com
Pull request #10467 github.com
Release v3.8.3 github.com
Release v4.3.4 github.com

Other livewire/livewire advisories

medium Livewire: Authorization bypass in #[Authorize] via reordered parameter keys and #[Json] execution order 2026-10-23
critical CVE-2025-54068: Livewire is vulnerable to remote command execution during component property update hydration 2025-07-17
high CVE-2024-47823: Livewire Remote Code Execution on File Uploads 2024-10-08
medium CVE-2024-21504: Cross-site Scripting in livewire/livewire 2024-03-19
medium $this->validate() returns all properties, not just validated ones 2020-09-22

Need help patching or upgrading? Laskyr does PHP and Laravel security fixes and upgrades. Tell us what you run and we reply with a plan and a price.

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Where this data comes from

Affected and fixed versions: the Packagist security advisories API (GitHub Advisory Database and FriendsOfPHP), the same data composer audit uses. Synced 2026-11-03.
Description, score, weakness and references: NIST National Vulnerability Database (NVD), checked 2026-11-04. This product uses data from the NVD API but is not endorsed or certified by the NVD.
Exploited-in-the-wild status: the CISA Known Exploited Vulnerabilities catalog, checked 2026-11-04.
Compiled by Daniel Lasek at Laskyr from the sources above. The summary, “who can exploit it”, “how to fix it” and hardening sections are our plain-English reading of the record and are generated from it. The quoted description is the record's own text. Spot an error? Tell us.