EUVD-2026-31209
GHSA-f53p-382v-8pj7
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessIdentify public page rendering fusion shortcodes
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DeliveryScrape fusion_load_nonce from page JavaScript
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ExploitPOST crafted base64 JSON to fusion_get_widget_markup AJAX
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ExecutionReach call_user_func() in conditional render helper
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PersistExecute arbitrary PHP as web server user
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ImpactEstablish webshell and persistence
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Input neutralization, injection prevention
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| Exploitation Conditions | Exploitation requires that the target WordPress site has the Avada Builder plugin at version 3.15.2 or earlier installed AND publishes at least one public-facing page containing a Post Cards ([fusion_post_cards]) or Table of Contents ([fusion_table_of_contents]) shortcode/element, because that page is what leaks the fusion_load_nonce in its JavaScript output to anonymous visitors. The vulnerable code path is the wp_conditional_tags case in Fusion_Builder_Conditional_Render_Helper::get_value(), reached via the wp_ajax_nopriv_fusion_get_widget_markup AJAX action; no WordPress login, no privileged role, and no user interaction by an admin are required. Limiting factor: sites running Avada Builder but with no public page emitting those two specific shortcode elements do not expose the nonce and therefore present a meaningfully higher bar for exploitation. |
| Impact | All signals point to a genuinely high-priority issue: CVSS 3.1 vector AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H reflects network-reachable, low-complexity, no-auth, no-user-interaction exploitation with full confidentiality, integrity, and availability impact, which is consistent with the described nopriv AJAX handler reaching call_user_func() on attacker data. EPSS and CISA KEV status were not provided in the input, so widespread exploitation cannot be confirmed; no public exploit identified at time of analysis. The Avada theme's large WordPress install base, the trivial nonce-bypass via any page rendering Post Cards or TOC shortcodes, and the direct PHP function injection primitive make automated mass-scanning highly likely once weaponized - this should be treated as a real priority rather than a high-CVSS-but-low-real-risk finding. Note: KEV/EPSS data is missing from the input, so listing status should be re-checked against CISA KEV and FIRST EPSS feeds before final prioritization. |
| Exploit ScenarioDerived | An unauthenticated attacker fetches any public page on the target site that contains a Post Cards or Table of Contents element, scrapes the fusion_load_nonce from the rendered JavaScript, then sends a POST to admin-ajax.php with action=fusion_get_widget_markup and a base64-encoded JSON payload whose wp_conditional_tags entry names an arbitrary PHP callable such as system or assert. The Fusion_Builder_Conditional_Render_Helper::get_value() handler passes that string to call_user_func(), executing the attacker's PHP under the web server account and yielding full site takeover. No public exploit identified at time of analysis, but the primitive is straightforward enough that mass-scanning weaponization is highly plausible. |
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Alert meAnalysisAIv1 – May 21, 2026
Unauthenticated remote code execution in the Avada Builder (fusion-builder) WordPress plugin versions up to and including 3.15.2 allows attackers to execute arbitrary PHP on affected sites by abusing an unsanitized call_user_func() invocation reachable through a public AJAX endpoint. Wordfence-reported issue affects any WordPress site running the Avada theme stack that exposes a Post Cards or Table of Contents element on a public page, since the protecting nonce is deterministically leaked in the page's JavaScript. No public exploit identified at time of analysis, but the CVSS 9.8 rating and trivial precondition (visiting one page that emits the nonce) make this high-priority.
RemediationAI
Upgrade Avada Builder to a version newer than 3.15.2 as soon as the vendor publishes a fixed release; the input data does not include an exact fix version, so released patched version not independently confirmed and administrators should consult the Avada changelog at https://avada.com/documentation/avada-changelog/ and the Wordfence advisory at https://www.wordfence.com/threat-intel/vulnerabilities/id/5dc72d78-d47c-4b36-8d69-8672e15ddf8c?source=cve to identify the patched build. Until a patched version is installed, remove the [fusion_post_cards] and [fusion_table_of_contents] shortcodes from all public pages so the fusion_load_nonce stops being leaked (this breaks those page elements but eliminates the reachable preauth nonce), and/or block the admin-ajax.php action=fusion_get_widget_markup request at the WAF or web server level (this disables legitimate widget-markup rendering for that action). As a defense-in-depth measure, restrict access to wp-admin/admin-ajax.php for anonymous users where business logic permits, accepting that this can break other plugins that rely on nopriv AJAX endpoints.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in euvd
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Technical ContextAI · show details
The vulnerability is a CWE-74 injection flaw in the PHP code path Fusion_Builder_Conditional_Render_Helper::get_value(), specifically the wp_conditional_tags branch, which decodes a base64 JSON blob from request input and passes attacker-controlled values directly to PHP's call_user_func() without any allowlist or callable validation. Exposure occurs through the AJAX action fusion_get_widget_markup, registered via wp_ajax_nopriv_fusion_get_widget_markup, which makes the handler reachable by unauthenticated visitors. The only protection is a WordPress nonce (fusion_load_nonce) generated for user ID 0 (anonymous); because that nonce is identical for all unauthenticated visitors and is rendered into the JavaScript of any public page that contains a [fusion_post_cards] or [fusion_table_of_contents] shortcode, it provides no real authorization barrier. CPE cpe:2.3:a:themefusion:avada_(fusion)_builder identifies the affected component as ThemeFusion's commercial Avada Builder plugin distributed with the Avada theme.
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Primary rating from Vendor (Wordfence) · only source for this CVE.
CVSS VectorVendor: Wordfence
DescriptionCVE.org
The Avada Builder (fusion-builder) plugin for WordPress is vulnerable to Unauthenticated Remote Code Execution via PHP Function Injection in versions up to and including 3.15.2. This is due to the wp_conditional_tags case in Fusion_Builder_Conditional_Render_Helper::get_value() passing attacker-controlled values from a base64-decoded JSON blob directly to call_user_func() without any allowlist validation. This is exploitable by unauthenticated attackers through the fusion_get_widget_markup AJAX endpoint, which is registered for non-privileged (unauthenticated) users via wp_ajax_nopriv_fusion_get_widget_markup. The endpoint is protected only by a nonce (fusion_load_nonce), but this nonce is generated for user ID 0 and is deterministically exposed in the JavaScript output of any public-facing page containing a Post Cards ([fusion_post_cards]) or Table of Contents ([fusion_table_of_contents]) element. This makes it possible for unauthenticated attackers to execute arbitrary code on affected sites.
Executive ViewAI
Any WordPress site using Avada Builder plugin (versions ≤3.15.2) faces immediate risk of complete server compromise through unauthenticated remote code execution. The vulnerability requires no credentials and is trivially exploitable to any visitor viewing common theme elements (Post Cards, Table of Contents), yet no vendor patch is available. Organizations must act urgently to identify affected sites and implement interim controls.
Deactivate fusion-builder plugin on all affected WordPress installations; implement Web Application Firewall rules to block vulnerable AJAX endpoints; restrict WordPress admin dashboard access via IP whitelist; enable server-side logging and alerting for exploitation attempts (POST /wp-admin/admin-ajax.php with suspicious action parameters); schedule daily vendor advisory checks for patch availability.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.
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