CVE-2026-12428: Auth Bypass (CVSS 6.5)

Description

The Blocks for ACF Fields plugin for WordPress is vulnerable to unauthorized access of data due to a missing capability check on the get_all_values() function in the /wp-json/acf-field-blocks/v1/values REST endpoint in versions up to, and including, 1.6.2. The permission_callback only verifies the generic publish_posts capability and the handler passes a user-supplied id parameter directly to get_field_objects() without verifying that the requesting user is authorized to read the target object. This makes it possible for authenticated attackers, with Author-level access and above, to read ACF field values from arbitrary posts (including private posts, drafts, posts by other users, and other ACF-supported objects) that they should not have access to.

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CVSS v3.1 Score

6.5

MEDIUM

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

EPSS — Exploit Prediction

0.0028

Probability of exploitation

0.20%

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-862 Missing Authorization

References

Other References

https://plugins.trac.wordpress.org/browser/acf-field-blocks/tags/1.5.0/inc/class-rest.php#L100 https://plugins.trac.wordpress.org/browser/acf-field-blocks/tags/1.5.0/inc/class-rest.php#L296 https://plugins.trac.wordpress.org/browser/acf-field-blocks/tags/1.5.0/inc/class-rest.php#L302 https://plugins.trac.wordpress.org/browser/acf-field-blocks/tags/1.6.0/inc/class-rest.php#L100 https://plugins.trac.wordpress.org/browser/acf-field-blocks/tags/1.6.0/inc/class-rest.php#L296 https://plugins.trac.wordpress.org/browser/acf-field-blocks/tags/1.6.0/inc/class-rest.php#L302 https://plugins.trac.wordpress.org/changeset?reponame=&old=3587876%40acf-field-blocks&new=3587876%40acf-field-blocks https://www.wordfence.com/threat-intel/vulnerabilities/id/fc48f75d-a2e8-49ea-9bfa-a27a61ff8a84?source=cve

Frequently Asked Questions

What is CVE-2026-12428? +

The Blocks for ACF Fields plugin for WordPress is vulnerable to unauthorized access of data due to a missing capability check on the get_all_values() function in the /wp-json/acf-field-blocks/v1/values REST endpoint in versions up to, and including, 1.6.2. The permission_callback only verifies the generic publish_posts capability and the handler passes a user-supplied id parameter directly to get_field_objects() without verifying that the requesting user is authorized to read the target object. This makes it possible for authenticated attackers, with Author-level access and above, to read ACF field values from arbitrary posts (including private posts, drafts, posts by other users, and other ACF-supported objects) that they should not have access to. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-12428? +

CVE-2026-12428 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0028, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-12428? +

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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