CVE-2023-53956: altervista flatnux · Unrestricted File Upload
Affects altervista flatnuxSource CVE Database V5
Not known to be exploited · CVSS 8.7 High.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.7% chance of exploitation in 30 days – higher than 55% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 19 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| altervista flatnux | Affected
| Fixed in– |
AI-suggested
- Immediately restrict administrative access to trusted personnel and enforce strong authentication mechanisms such as multi-factor authentication (MFA).
- Monitor and audit all file uploads through the Flatnux file manager for suspicious or unauthorized PHP files.
- Implement web application firewall (WAF) rules to detect and block malicious file uploads and execution attempts.
- Isolate the web root directory with strict permissions to prevent execution of unauthorized scripts.
- If possible, disable or limit file upload functionality for admin users until a patch is available.
- Regularly review and update user privileges to minimize the number of admin accounts.
- Maintain up-to-date backups to enable rapid recovery in case of compromise.
- Engage with Altervista or Flatnux developers for official patches or security advisories and apply them promptly once released.
- Conduct penetration testing and vulnerability assessments focused on file upload mechanisms to identify similar weaknesses.
- Educate administrators on the risks of uploading untrusted files and enforce secure operational procedures.
Description
Flatnux 2021-03.25 contains an authenticated file upload vulnerability that allows administrative users to upload arbitrary PHP files through the file manager. Attackers with admin credentials can upload malicious PHP scripts to the web root directory, enabling remote code execution on the server.