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Blocksy Companion Pro CVE-2026-40783

| EUVDEUVD-2026-37605 CRITICAL
Code Injection (CWE-94)
2026-06-17 Patchstack
9.9
CVSS 3.1 · Vendor: Patchstack
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain Contributor WordPress account
  2. Delivery
    Send crafted request to Blocksy Companion Pro endpoint
  3. Exploit
    Inject PHP into vulnerable code sink
  4. Execution
    Plugin evaluates attacker input
  5. Persist
    Execute code as web server user
  6. Impact
    Pivot to full WordPress and host takeover

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Code injection prevention, sandbox exec
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires an authenticated WordPress account with at least the Contributor role on a site where Blocksy Companion Pro <= 2.1.37 is installed and active (PR:L in the CVSS vector). No user interaction is needed (UI:N) and the attack is reachable over the network via standard HTTP(S) to the WordPress admin or front-end endpoints exposed by the plugin. Exploitation is limited to sites that both run the Pro edition (not necessarily the free Blocksy Companion) and grant Contributor or higher accounts to potentially untrusted users - single-author or admin-only installations sharply reduce the attacker population.

Impact

The CVSS vector (AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H) shows network-reachable, low-complexity exploitation requiring only low (Contributor) privileges, no user interaction, and a scope change with full CIA impact - a realistic worst case for any multi-author WordPress site. This is not in the CISA KEV catalog and no EPSS score was supplied, so widespread mass exploitation is not yet evidenced; however, Contributor accounts are commonly available on blogs, news sites, and membership platforms, which materially expands the realistic attacker pool. Note that the input does not include an EPSS probability or POC indicator, so the practical exploitation likelihood cannot be quantitatively compared against the high CVSS - sites that grant Contributor roles to untrusted users should treat this as a priority regardless.

Exploit ScenarioDerived

An attacker registers or compromises a low-privilege Contributor account on a WordPress site running Blocksy Companion Pro <= 2.1.37, then submits a crafted post, shortcode, or plugin action that injects PHP code into a vulnerable sink. The plugin evaluates the attacker-controlled input on the server, yielding code execution as the web server user and full takeover of the WordPress installation and any co-hosted data.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.
No patch listed yet 0.5% exploitation probability (EPSS)

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AnalysisAIv1 – Jun 17, 2026

Remote code execution in Blocksy Companion Pro (Creative Themes) versions 2.1.37 and earlier allows authenticated users with Contributor-level WordPress privileges to inject and execute arbitrary code on the underlying server. The flaw carries a CVSS 3.1 base score of 9.9 with scope change, reflecting that successful exploitation breaks out of the WordPress application context. No public exploit identified at time of analysis, but Patchstack has catalogued the issue in its WordPress vulnerability database.

RemediationAI

Upstream fix available per Patchstack advisory; released patched version not independently confirmed in the provided data - administrators should upgrade Blocksy Companion Pro to the next release after 2.1.37 as published by Creative Themes and monitor https://patchstack.com/database/wordpress/plugin/blocksy-companion-pro/vulnerability/wordpress-blocksy-companion-pro-plugin-2-1-37-remote-code-execution-rce-vulnerability for the exact fixed version. Until patched, restrict who can hold the Contributor role (remove untrusted authors, disable open registration that defaults to Contributor), or temporarily deactivate Blocksy Companion Pro accepting the trade-off of losing its site-building features. A WordPress WAF such as Patchstack or Wordfence with a virtual patch for this CVE can also block exploitation, at the cost of an additional dependency and potential false positives on legitimate editor activity.

Affected VersionsENISA

Blocksy Companion Pro n/a ≤2.1.37

Affected Packages

euvd blocksy_companion_pro no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Blocksy Companion Pro is a premium WordPress plugin from Creative Themes that extends the Blocksy theme with site-building features such as custom post types, header/footer builders, and content blocks. The root cause is CWE-94 (Improper Control of Generation of Code, i.e. Code Injection), which typically arises in WordPress plugins when user-supplied input is passed into shortcode handlers, template rendering helpers, or eval/include-style sinks without proper sanitization. The CPE cpe:2.3:a:creative_themes:blocksy_companion_pro:*:*:* indicates all versions through 2.1.37 are in scope across deployments.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (Patchstack) PRIMARY 9.9 CRITICAL
AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
vuln.today AI 9.9 CRITICAL

Network-reachable WordPress endpoint (AV:N/AC:L), Contributor role required (PR:L), no interaction (UI:N), PHP code execution breaks WordPress app boundary into host (S:C) with full CIA impact.

3.1 AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Primary rating from Vendor (Patchstack).

CVSS VectorVendor: Patchstack

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

Contributor Remote Code Execution (RCE) in Blocksy Companion Pro <= 2.1.37 versions.

Executive ViewAI

Why It Matters

Blocksy Companion Pro, a widely-deployed WordPress plugin, contains a critical remote code execution vulnerability (CVE-2026-40783, CVSS 9.9) affecting versions 2.1.37 and earlier with no vendor patch currently available. Exploitation could allow attackers to execute arbitrary commands on affected servers and compromise all data hosted on those systems. Organizations using this plugin must implement urgent mitigations to prevent server takeover and data breach.

Business Impact: Severe
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: (1) Disable plugin if business requirements allow; (2) Restrict or remove Contributor-level WordPress accounts to reduce attack surface; (3) Deploy Web Application Firewall (WAF) rules to detect exploitation attempts targeting this plugin; (4) Implement IP whitelisting for WordPress administrative access; (5) Enable comprehensive logging and monitoring of authentication events and server file modifications for incident detection.

Threat Intelligence Overview

EPSS Score
0.5%
Top 59% exploitable
Data Quality
5 sources
Confidence: Medium

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.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.5%
Patch available No
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
Very High
Technical Impact
Total

Priority Score

51
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +50
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Code Injection CRITICAL

Code injection occurs when an application accepts user input and passes it directly into a language interpreter or evaluator without proper sanitization.

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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