CVE-2026-89435: Injection (CVSS 8.8)

Description

The Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More plugin for WordPress is vulnerable to Arbitrary Plugin Installation in all versions up to, and including, 6.35 via the 'file_url' parameter parameter. This is due to insufficient URL prefix validation in validate_url_is_in_s3_bucket() and a permission callback that relies solely on a shared token obtainable by any user with the delegable frm_view_forms capability, without checking install_plugins or activate_plugins capabilities. This makes it possible for authenticated attackers, with subscriber-level access and above, to install arbitrary plugins on the server. Exploitation additionally requires that the site is free-only (Formidable Pro is NOT installed).

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CVSS v3.1 Score

8.8

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0039

Probability of exploitation

0.34%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-74 CWE-74

References

Other References

https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/controllers/FrmAddonsController.php#L1459 https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/controllers/FrmAddonsController.php#L1489 https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/controllers/FrmAddonsController.php#L1514 https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/controllers/FrmAppController.php#L1167 https://plugins.trac.wordpress.org/browser/formidable/tags/6.35/classes/helpers/FrmAppHelper.php#L4934 https://plugins.trac.wordpress.org/changeset/3746820/formidable/trunk/classes/controllers/FrmAddonsController.php https://plugins.trac.wordpress.org/changeset?reponame=&new=3750372%40formidable%2Ftags%2F7.0&old=3688662%40formidable%2Ftags%2F6.35 https://www.wordfence.com/threat-intel/vulnerabilities/id/87661de6-e835-495e-9bd2-4d64b4718108?source=cve

Frequently Asked Questions

What is CVE-2026-89435? +

The Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More plugin for WordPress is vulnerable to Arbitrary Plugin Installation in all versions up to, and including, 6.35 via the 'file_url' parameter parameter. This is due to insufficient URL prefix validation in validate_url_is_in_s3_bucket() and a permission callback that relies solely on a shared token obtainable by any user with the delegable frm_view_forms capability, without checking install_plugins or activate_plugins capabilities. This makes it possible for authenticated attackers, with subscriber-level access and above, to install arbitrary plugins on the server. Exploitation additionally requires that the site is free-only (Formidable Pro is NOT installed). It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2026-89435? +

CVE-2026-89435 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0039, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-89435? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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