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Security Independently confirmed2 publishers 3 min read Published Updated

Forminator's 9.8 upload bug was fixed on July 31. The hard part is knowing you run it

Unauthenticated attackers can drop PHP onto WordPress sites running Forminator 1.56.1 or earlier. The install base is 600,000; the exposed subset depends on how the forms were built.

The Watch · Security desk

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What happened

  • A critical flaw in the Forminator Forms WordPress plugin is tracked as CVE-2026-15748 and rated 9.8 out of 10.0 on CVSS; it was disclosed in a Wordfence report.
  • Forminator Forms has more than 600,000 active installations.
  • The vulnerability has been addressed in Forminator version 1.56.2, released on July 31, 2026.
  • The flaw is an arbitrary file upload issue residing in the handle_file_upload() function, stemming from a lack of sufficient file type validation in user-supplied input.
  • Wordfence: the issue is due to insufficient file type validation in handle_file_upload, where the dangerous-extension blocklist performs exact-key matching that is bypassed by pipe-alternative MIME type keys, combined with a public submission handler that trusts attacker-controlled upload field configuration injected via a forged Select field value.

Why it matters

Wordfence has disclosed CVE-2026-15748, an arbitrary file upload flaw rated 9.8 out of 10 on CVSS in Forminator Forms, a WordPress plugin with more than 600,000 active installations [2][1]. The fix, version 1.56.2, has been available since July 31, 2026, which makes anything still exposed a records problem rather than a patching one [3].

The bug sits in the plugin's handle_file_upload() function and stems from insufficient validation of user-supplied file types [4]. According to Wordfence, the dangerous-extension blocklist performs exact-key matching that can be bypassed with pipe-alternative MIME type keys, while a public submission handler trusts upload field configuration that an attacker injects through a forged Select field value [5]. The consequence, in Wordfence's description, is that unauthenticated attackers can upload arbitrary files including executable PHP, leading to remote code execution and complete site compromise [6]. The flaw was reported by a researcher using the alias "daroo" [13]. Every version up to and including 1.56.1 is affected [7].

The 600,000 number is an install count, not a count of exploitable sites, and the gap between the two is where the work is. Exploitation requires a form that contains both a File Upload field and a Select field [8]. In the default configuration, uploads go to a directory protected by an .htaccess file that prevents PHP execution [9]. The dangerous case is a site where an administrator configured a Custom File Upload Storage root: Wordfence says the .htaccess file there is created only when it is first needed, during a frontend request in which the WordPress helper responsible for writing it is not loaded [10]. On that kind of site, simply requesting the uploaded file is enough to make the web server execute the attacker's PHP [11].

That is three conditions deep, and each one was set by someone building a contact form, not by someone maintaining an asset register.

The same week brought a second 9.8 in the same shape. Wordfence flagged CVE-2026-15826, an authentication bypass in User Profile Builder, which has more than 40,000 active installations, patched on July 16, 2026 in version 3.16.5 [14][15]. It is only exploitable where the plugin's Automatically Log In setting is enabled [16]. Wordfence attributes it to wppb_log_in_user() calling absint() on the return value of wp_insert_user() before the is_wp_error() check: a registration with a 61 to 70 character username is rejected by WordPress core with a WP_Error object, absint() coerces that to the integer 1, and the plugin binds and returns a transient-backed autologin nonce tied to user ID 1 [17]. That yields unauthenticated login as the administrator account and full site takeover [18].

Two patches, fifteen days apart, covering more than 640,000 installations between them [20][21]. Neither disclosure, as reported, describes exploitation in the wild; the vendor guidance is to update both plugins and verify installations are current [12].

What to watch: in both cases the deciding factor is a configuration choice, not plugin presence [19]. The useful artifact is a list of which sites run Forminator with a File Upload and Select field on the same form, and which of those point at a custom storage root. Without it, the answer to whether an estate is exposed is a guess dressed up as a version number.

Clarity's read

What the record supports and how the coverage leans. The claims behind it follow.

Reality

Evidence72
Adoption45
Hype gap+30
Incentives
Not scored
Confidence68
Why these scores

Claim ledger

Ranked by verification strength, evidence, and original report placement.

  1. [1]

    Forminator Forms has more than 600,000 active installations.

    Reported SupportedView cited source
  2. [2]

    A critical flaw in the Forminator Forms WordPress plugin is tracked as CVE-2026-15748 and rated 9.8 out of 10.0 on CVSS; it was disclosed in a Wordfence report.

    Reported Supported Source: Wordfence, via The Hacker NewsView cited source
  3. [3]

    The vulnerability has been addressed in Forminator version 1.56.2, released on July 31, 2026.

    Reported SupportedView cited source
  4. [4]

    The flaw is an arbitrary file upload issue residing in the handle_file_upload() function, stemming from a lack of sufficient file type validation in user-supplied input.

    Reported SupportedView cited source
  5. [5]

    Wordfence: the issue is due to insufficient file type validation in handle_file_upload, where the dangerous-extension blocklist performs exact-key matching that is bypassed by pipe-alternative MIME type keys, combined with a public submission handler that trusts attacker-controlled upload field configuration injected via a forged Select field value.

    Reported Supported Source: WordfenceView cited source
  6. [6]

    Wordfence: the vulnerability makes it possible for unauthenticated attackers to upload arbitrary files, including executable PHP files, to a vulnerable site, which can lead to remote code execution and complete site compromise.

    Reported Supported Source: WordfenceView cited source
  7. [7]

    The vulnerability impacts all versions of the plugin before and including 1.56.1.

    Reported SupportedView cited source
  8. [8]

    A key prerequisite for successful exploitation is that the site must have a form containing both a File Upload field and a Select field.

    Reported SupportedView cited source
  9. [9]

    In the default configuration, files are uploaded to a directory protected by an .htaccess file that prevents PHP execution.

    Reported SupportedView cited source
  10. [10]

    If a site administrator has configured a Custom File Upload Storage root, it may not have the same safeguard, because the .htaccess file is created only when it is first needed, during a frontend request where the WordPress helper responsible for writing the .htaccess file is not loaded.

    Reported Supported Source: WordfenceView cited source
  11. [11]

    As a result, requesting the uploaded file is enough to cause the web server to execute the attacker-controlled PHP code.

    Reported SupportedView cited source
  12. [12]

    Site owners who have either of the two plugins are advised to apply the updates as soon as possible and ensure their installations are up to date; the report does not describe exploitation in the wild.

    Reported SupportedView cited source
  13. [13]

    The vulnerability was discovered and reported by a security researcher who goes by the online alias "daroo".

    Reported SupportedView cited source
  14. [14]

    Wordfence highlighted a critical authentication bypass bug in User Profile Builder, tracked as CVE-2026-15826 with a CVSS score of 9.8, in a plugin with more than 40,000 active WordPress installations.

    Reported SupportedView cited source
  15. [15]

    CVE-2026-15826 was patched on July 16, 2026, with the release of User Profile Builder version 3.16.5; all prior versions are affected.

    Reported SupportedView cited source
  16. [16]

    CVE-2026-15826 is only exploitable on sites where the plugin's Automatically Log In setting is enabled.

    Reported SupportedView cited source
  17. [17]

    Wordfence: wppb_log_in_user() calls absint() on the return value of wp_insert_user() before performing an is_wp_error() check; when a registration is submitted with a 61-70 character username, WordPress core rejects it with a WP_Error object, but absint() coerces that object to the integer 1 before the error check can short-circuit execution, causing the plugin to bind and return a transient-backed autologin nonce tied to user ID 1.

    Reported Supported Source: WordfenceView cited source
  18. [18]

    Wordfence: this makes it possible for unauthenticated attackers to log in as the site's Administrator account (user ID 1), resulting in full administrative takeover of the site.

    Reported Supported Source: WordfenceView cited source
  19. [19]

    In both vulnerabilities, exploitability is gated on operator configuration rather than plugin presence alone: Forminator requires a form with both a File Upload and a Select field, with PHP execution depending on a Custom File Upload Storage root, and User Profile Builder requires the Automatically Log In setting.

    Derived Supported
  20. [20]

    The two patches were released fifteen days apart.

    Derived Supported
  21. [21]

    The two affected plugins have more than 640,000 active installations between them.

    Derived Supported

Sources

2 independent publishers whose own reporting we read for this story.

  1. securityweek.com

    1 article · August 18, 2026

    300,000 WordPress Sites Potentially Exposed to Hacking Due to Form Plugin Flaw
  2. thehackernews.com

    1 article · August 17, 2026

    Forminator WordPress Flaw Can Enable Unauthenticated RCE via Malicious PHP Uploads

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