CVE-2026-2839

Full vulnerability record from the local CVENow database.

Description

The Advanced Custom Fields: Extended plugin for WordPress is vulnerable to unauthorized access of data and triggering of server-side actions in all versions up to, and including, 0.9.2.7. This is due to multiple AJAX handlers registered for unauthenticated users (`wp_ajax_nopriv_*`) that fail to implement proper `current_user_can()` authorization checks. While these handlers use ACF's `acf_verify_ajax()` function to validate cryptographic nonces, the `acf_nonce` values are generated for guest users and publicly exposed in the page source of any frontend page utilizing an ACF form. This makes it possible for unauthenticated attackers to extract the guest nonce and bypass WordPress visibility permissions, leading to the unauthorized disclosure of post titles and internal Flexible Content layout structures. The vulnerability was partially patched in version 0.9.2.4.

Severity

MEDIUM

CVSS score

5.3 (v3.1)

Vulnerability status

Deferred

Source identifier

[email protected]

Published

2026-10-28 07:16:48.367000

Last modified

2026-10-29 02:16:52.227000

View original CVE JSON

{
  "id": "CVE-2026-2839",
  "sourceIdentifier": "[email protected]",
  "published": "2026-10-28T07:16:48.367",
  "lastModified": "2026-10-29T02:16:52.227",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "The Advanced Custom Fields: Extended plugin for WordPress is vulnerable to unauthorized access of data and triggering of server-side actions in all versions up to, and including, 0.9.2.7. This is due to multiple AJAX handlers registered for unauthenticated users (`wp_ajax_nopriv_*`) that fail to implement proper `current_user_can()` authorization checks. While these handlers use ACF's `acf_verify_ajax()` function to validate cryptographic nonces, the `acf_nonce` values are generated for guest users and publicly exposed in the page source of any frontend page utilizing an ACF form. This makes it possible for unauthenticated attackers to extract the guest nonce and bypass WordPress visibility permissions, leading to the unauthorized disclosure of post titles and internal Flexible Content layout structures. The vulnerability was partially patched in version 0.9.2.4."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "hwk-fr",
          "product": "Advanced Custom Fields: Extended",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "0",
              "lessThanOrEqual": "0.9.2.7",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "LOW",
          "integrityImpact": "NONE",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-10-29T01:33:28.630428Z",
          "id": "CVE-2026-2839",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-862"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://plugins.trac.wordpress.org/browser/acf-extended/trunk/includes/fields/field-advanced-link.php#L25",
      "source": "[email protected]"
    },
    {
      "url": "https://plugins.trac.wordpress.org/browser/acf-extended/trunk/includes/fields/field-advanced-link.php#L603",
      "source": "[email protected]"
    },
    {
      "url": "https://plugins.trac.wordpress.org/browser/acf-extended/trunk/includes/fields/field-flexible-content-async.php#L151",
      "source": "[email protected]"
    },
    {
      "url": "https://plugins.trac.wordpress.org/browser/acf-extended/trunk/includes/fields/field-flexible-content-async.php#L24",
      "source": "[email protected]"
    },
    {
      "url": "https://plugins.trac.wordpress.org/changeset/3516027/",
      "source": "[email protected]"
    },
    {
      "url": "https://plugins.trac.wordpress.org/changeset/3754818/",
      "source": "[email protected]"
    },
    {
      "url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/9954ef37-bae0-48fb-9654-ff54750c46c2?source=cve",
      "source": "[email protected]"
    }
  ]
}