CVE-2021-28931
Arbitrary file upload in Fork CMS
Arbitrary file upload vulnerability in Fork CMS 5.9.2 allows attackers to create or replace arbitrary files in the /themes directory via a crafted zip file uploaded to the Themes panel.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
Arbitrary file upload vulnerability in Fork CMS 5.9.2 allows attackers to create or replace arbitrary files in the /themes directory via a crafted zip file uploaded to the Themes panel.
- Record
CVE-2021-28931- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 6.5 Medium
AV:N/AC:L/Au:S/C:P/I:P/A:P - Weakness
- CWE-434
- Updated
- 2026-11-02
CVE List No score
Arbitrary file upload vulnerability in Fork CMS 5.9.2 allows attackers to create or replace arbitrary files in the /themes directory via a crafted zip file uploaded to the Themes panel.
- Record
CVE-2021-28931- Updated
- 2026-11-02
EUVDEUVD-2021-2001 No score
Arbitrary file upload vulnerability in Fork CMS 5.9.2 allows attackers to create or replace arbitrary files in the /themes directory via a crafted zip file uploaded to the Themes panel.
- Record
EUVD-2021-2001- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-748f-wv76-x9hg
Arbitrary file upload in Fork CMS
Arbitrary file upload vulnerability in Fork CMS 5.9.2 allows attackers to create or replace arbitrary files in the /themes directory via a crafted zip file uploaded to the Themes panel.
- Record
GHSA-748f-wv76-x9hg- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-434
- Updated
- 2026-11-02
OSV
Arbitrary file upload vulnerability in Fork CMS 5.9.2 allows attackers to create or replace arbitrary files in the /themes directory via a crafted zip file uploaded to the Themes panel.
- Record
CVE-2021-28931- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVGHSA-748f-wv76-x9hg
Arbitrary file upload in Fork CMS
Arbitrary file upload vulnerability in Fork CMS 5.9.2 allows attackers to create or replace arbitrary files in the /themes directory via a crafted zip file uploaded to the Themes panel.
- Record
GHSA-748f-wv76-x9hg- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-434
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
forkcms/forkcmsPackagist |
through 5.9.2 | 5.9.3 |
forkcms/forkcmsPackagist |
before 5.9.3, plus listed versions 3.5.03.5.13.6.03.6.13.6.2 Show 45 moreShow less3.6.33.6.43.6.53.6.63.73.7.13.7.23.7.33.8.03.8.13.8.23.8.33.8.43.8.53.8.63.8.73.9.03.9.13.9.23.9.33.9.43.9.53.9.64.0.04.0.14.0.24.0.34.0.44.0.54.0.64.1.04.1.14.1.24.2.04.2.14.2.24.2.34.2.44.3.04.3.14.4.04.4.14.5.04.5.14.5.2 |
5.9.3 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-28931 is a high vulnerability (CVSS 8.8) in Fork-cms Fork Cms, published July 7, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.21%, the 68th percentile. Fixed in forkcms/forkcms 5.9.3.
References
Left out here: 35 versions. The JSON record has them.