CVE-2026-78363

MW WP Form < 5.1.5 - Unauthenticated Arbitrary Shortcode Execution

2026-08-27 00:00
Jakub Herman

Strategic Overview

Status
Patched in 5.1.5
Affected Plugin
MW WP Form
Affected Version
< 5.1.5
CVSS
6.5Medium
Weakness type
CWE-94 · Improper Control of Generation of Code ('Code Injection')
CVE
CVE-2026-78363
View all MW WP Form vulnerabilities

At a glance

CVE-2026-78363 is a medium-severity Improper Control of Generation of Code ('Code Injection') vulnerability in the MW WP Form WordPress plugin, affecting versions < 5.1.5. It carries a CVSS score of 6.5 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 5.1.5; sites on affected versions should update now. Disclosed August 2026, reported by Jakub Herman.

Vulnerability Overview

The MW WP Form plugin for WordPress is vulnerable to Arbitrary Shortcode Execution in all versions up to 5.1.5. This is due to missing neutralization of shortcode brackets in user-supplied values before they are substituted into the completion page content and processed by the WordPress shortcode parser. This makes it possible for unauthenticated attackers to execute arbitrary shortcodes registered on the site by injecting shortcode syntax into form fields that are echoed back on the completion page.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user.

CWE-94: Improper Control of Generation of Code ('Code Injection')

Reaching this weakness in MW WP Form < 5.1.5 takes no account at all. Code injection means input from a request reaches a language construct that evaluates code, so the attacker's text is executed rather than treated as data.

The injected code runs with the web server's privileges, giving the attacker the same access to the database and filesystem as WordPress itself. For MW WP Form the fix is 5.1.5: builds < 5.1.5 are affected, anything from 5.1.5 onward is not.

Remediation

Update to version 5.1.5, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: MW WP Form 5.1.5 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Login Security

External References

https://www.cve.org/CVERecord?id=CVE-2026-78363https://www.wordfence.com/threat-intel/vulnerabilities/id/116e7099-2e30-4369-971c-85479709b99fhttps://nvd.nist.gov/vuln/detail/CVE-2026-78363

Related records

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