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CVE-2021-28931

25
FAUCET Score

CVE-2021-28931 is an arbitrary file upload vulnerability affecting Fork CMS version 5.9.2, allowing authenticated attackers to create or overwrite files within the /themes directory by uploading a specially crafted ZIP file. This vulnerability carries a high CVSS score of 8.8, indicating a severe risk with low attack complexity and potential for high impact on confidentiality, integrity, and availability. While no active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion has been observed, the underlying CWE-434 (Unrestricted Upload of File with Dangerous Type) highlights a critical security flaw.

Impacted Technologies

VendorProductVersion(s)CPE
5.9.2CPE matchmatch criteria
cpe:2.3:a:fork-cms:fork_cms:5.9.2:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.21%
Probability of exploitation in next 30 days
EPSS Percentile
65.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0121 is in the 62nd percentile among its peer group of 17,844 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

composerpatch availablevia ghsa
Product: forkcms/forkcmsFixed in: 5.9.3

Vendor Advisories (1)

composerGHSA-748f-wv76-x9hghigh

Arbitrary file upload in Fork CMS

Sep 8, 2021

References

github.com / bousalman/ForkCMS-arbitrary-upload/blob/main/README.md
Third Party Advisory
github.com / forkcms/forkcms/releases/tag/5.9.2
Release NotesThird Party Advisory