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CVE-2021-20866

23
FAUCET Score

CVE-2021-20866 describes a missing authorization vulnerability in Advanced Custom Fields (ACF) and ACF Pro versions prior to 5.11, allowing unauthorized access to user list information. Rated 6.5 Medium on the CVSS scale, this vulnerability requires low privileges and network access for an attacker to achieve high confidentiality impact without user interaction. While no public exploit code or active exploitation has been observed, and community discussion is minimal, organizations using affected ACF versions should prioritize patching to mitigate this information disclosure risk.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.11CPE matchmatch criteria
cpe:2.3:a:advancedcustomfields:advanced_custom_fields:*:*:*:*:*:wordpress:*:*
< 5.11CPE matchmatch criteria
cpe:2.3:a:advancedcustomfields:advanced_custom_fields:*:*:*:*:pro:wordpress:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.66%
Probability of exploitation in next 30 days
EPSS Percentile
74.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0166 is in the 87th percentile among its peer group of 21,974 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

jvn.jp / en/jp/JVN09136401/index.html
Third Party Advisory
wordpress.org / plugins/advanced-custom-fields
Third Party Advisory
advancedcustomfields.com
Vendor Advisory