Deserialization of Untrusted DataWeakness · CWE-502

CVE-2026-5127

HIGH · 8.8 CVSS v3.1 Published 2026-05-08

Mitigation only

No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.

See remediation →

94/100

Remediation priority · Urgent

Remotely reachable Zero-click

Official description

NVD · unedited

The User Frontend: AI Powered Frontend Posting, User Directory, Profile, Membership & User Registration plugin for WordPress is vulnerable to Deserialization of Untrusted Data in versions up to, and including, 4.3.1 This is due to insufficient input validation and type checking on the wpuf_files parameter during form submission, combined with unconditional deserialization via maybe_unserialize() when displaying post content. This makes it possible for authenticated attackers, with Subscriber-level access and above, to inject arbitrary PHP objects, which can be leveraged to execute arbitrary code, delete arbitrary files, or perform other malicious actions if a POP chain is present on the target system.

Technical summary

dbcve analysis · high confidence

This is a PHP Object Injection vulnerability in the User Frontend WordPress plugin. The plugin fails to properly validate the wpuf_files parameter during form submission and uses unsafe deserialization (maybe_unserialize()) when displaying post content. Authenticated attackers with Subscriber-level access can inject arbitrary PHP objects, potentially leading to code execution if a POP chain exists.

MitigationUpdate the plugin to a patched version beyond 4.3.1. If no update is available, disable the plugin or implement input validation/allowlisting on the wpuf_files parameter and remove unconditional deserialize calls.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown

From the vector

Attack vector: Network
Complexity: Low
Privileges: Low
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Verify User Frontend plugin is installed

Check the WordPress plugins directory or admin panel for the User Frontend plugin. Look for 'wp-user-frontend' or similar plugin files in wp-content/plugins/

Affected if The User Frontend plugin is installed and active
Check installed plugin version

Navigate to WordPress Admin > Plugins > User Frontend and note the version number, or inspect the plugin main PHP file header for the 'Version' tag

Affected if The installed version is 4.3.1 or earlier, or the version cannot be determined (assume affected)
Confirm post submission forms are enabled

Check if any User Frontend post forms are published and accessible. Look for forms created with the plugin in wp-admin/admin.php?page=wpuf_post_form or by searching for wpuf shortcodes in posts/pages

Affected if Active post submission forms exist that accept the wpuf_files parameter
Verify unauthenticated or low-privilege access exists

Check WordPress user roles. Look for Subscriber-level accounts or test if the post submission form is accessible to unauthenticated users (wpuf_form as a shortcode)

Affected if Subscriber-level users exist or forms allow submissions from unauthenticated users

If the User Frontend plugin is installed at version 4.3.1 or earlier AND has active post submission forms accessible to Subscriber-level or unauthenticated users, the environment is affected by this PHP Object Injection vulnerability.

Generated from the published advisory. Verify against your own configuration.

Remediation

From vendor data

Mitigation available No clean upgrade yet — mitigate in the meantime

Mitigation

Update the plugin to a patched version beyond 4.3.1. If no update is available, disable the plugin or implement input validation/allowlisting on the wpuf_files parameter and remove unconditional deserialize calls.

Have this fixed Scoped from the published advisory

Consultation2.0 h
Implementation4.0 h
Testing3.0 h
Review / QA2.0 h

11.0 hours of engineering $1,930

Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.

Scan for this in your stack

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References

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-5127 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2026-5127?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

A fix existsA vendor remedy is published

Severity 8.8 High

Exploit likelihood EPSS, next 30 days 1.0%

Remediation

A high-priority fix

Have this fixed 11 hrs · Moderate

Typical engagement from $1,930

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2026-5127 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

Check your environment

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

CVSS breakdown

Am I affected?

Remediation

References