CVE-2026-22398: Mikado-Themes Fleur Auth Bypass Flaw

CVE-2026-22398 Overview

CVE-2026-22398 is an Insecure Direct Object Reference (IDOR) vulnerability in the Mikado-Themes Fleur WordPress theme. The flaw is categorized as Authorization Bypass Through User-Controlled Key [CWE-639] and affects Fleur versions up to and including 2.0. An authenticated attacker with low privileges can manipulate user-controlled identifiers to access or modify resources belonging to other users. The issue stems from incorrectly configured access control checks that rely on client-supplied keys without verifying ownership.

Critical Impact

Authenticated low-privilege users can bypass access controls to read or modify objects owned by other users within affected Fleur theme installations.

Affected Products

• Mikado-Themes Fleur WordPress theme: versions up to and including 2.0
• WordPress sites deploying the Fleur theme with default access control settings
• Installations exposing Fleur theme endpoints to authenticated users

Discovery Timeline

• 2026-01-22 - CVE-2026-22398 published to NVD
• 2026-04-28 - Last updated in NVD database

Technical Details for CVE-2026-22398

Vulnerability Analysis

The vulnerability resides in the Fleur theme's handling of object identifiers supplied through user input. The application accepts identifier parameters from authenticated requests and uses them to fetch or operate on backend resources. Authorization checks fail to verify that the requesting user owns or has rights to the referenced object.

An attacker with a valid low-privilege account can substitute predictable or enumerable identifiers in requests. The server processes these substitutions and returns or modifies data belonging to other accounts. The attack requires network access and low privileges, with no user interaction.

The CWE-639 classification confirms the root issue is reliance on user-controlled keys for authorization decisions. Confidentiality remains intact in most paths, but integrity and availability of user-owned resources can be affected through unauthorized writes or deletions.

Root Cause

The Fleur theme constructs database or object lookups using identifiers passed directly from request parameters. The code path does not enforce a server-side check that binds the identifier to the authenticated session. Missing ownership validation allows horizontal privilege escalation across user accounts.

Attack Vector

Exploitation requires an authenticated session on a WordPress site running Fleur 2.0 or earlier. The attacker sends crafted HTTP requests substituting object identifiers with values belonging to other users. No specialized tooling is required beyond a standard HTTP client. Refer to the Patchstack advisory for detailed technical context.

Detection Methods for CVE-2026-22398

Indicators of Compromise

• Unexpected modifications to user-owned objects originating from accounts that do not own those resources
• Repeated HTTP requests from a single authenticated session iterating through sequential or enumerated identifier values
• Access log entries showing low-privilege accounts touching administrative or premium-tier object identifiers

Detection Strategies

• Correlate web server logs to flag authenticated requests where the object owner does not match the session user
• Deploy WordPress security plugins that audit IDOR patterns and log unauthorized cross-account access attempts
• Review the Fleur theme audit trail for object access events involving identifiers outside the requester's normal scope

Monitoring Recommendations

• Enable verbose access logging on WordPress endpoints exposed by the Fleur theme
• Alert on high-volume requests containing numeric identifier parameters from a single authenticated user
• Monitor database write operations against user-scoped tables for anomalous cross-account activity

How to Mitigate CVE-2026-22398

Immediate Actions Required

• Identify all WordPress instances running the Mikado-Themes Fleur theme and inventory installed versions
• Restrict authenticated access to Fleur theme functionality until a patched release is applied
• Audit recent activity logs for evidence of cross-account object access by low-privilege users

Patch Information

No fixed version is identified in the current advisory. Refer to the Patchstack vulnerability database entry and vendor channels for updates. Apply any released patch as soon as Mikado-Themes publishes a fixed version above 2.0.

Workarounds

• Switch to an alternative WordPress theme until Mikado-Themes ships a fix
• Deploy a Web Application Firewall rule blocking requests that pass object identifiers outside the requester's owned scope
• Limit authenticated user registration on sites exposing Fleur functionality to reduce the pool of potential attackers

# Configuration example: WAF rule sketch blocking suspicious IDOR patterns
# Adjust patterns to match Fleur theme endpoints in your environment
SecRule REQUEST_URI "@rx /wp-admin/admin-ajax\.php" \
  "chain,deny,status:403,id:1026223981,msg:'Possible Fleur IDOR attempt'"
SecRule ARGS_NAMES "@rx ^(id|user_id|object_id)$" \
  "chain"
SecRule ARGS:id "@rx ^[0-9]+$" \
  "setvar:tx.fleur_idor_score=+1"