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VulnerabilityPublished

CVE-2023-53933: s9y Serendipity · Unrestricted File Upload

Affects s9y SerendipitySource CVE Database V5

0

Not known to be exploited · CVSS 8.7 High.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 4.0 base score
8.7High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.0% chance of exploitation in 30 days – higher than 63% 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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 17 Dec 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
s9y SerendipityAffected
  • =2.4.0
Fixed in–

AI-suggested

Immediate mitigation involves upgrading Serendipity to a version where this vulnerability is patched once available. In the absence of a patch, organizations should implement strict file upload restrictions, including whitelisting allowed file types and blocking .phar and other executable extensions at the web server or application firewall level. Employing Web Application Firewalls (WAFs) with rules to detect and block suspicious file uploads can reduce risk. Restrict upload permissions to only trusted authenticated users and enforce strong authentication mechanisms such as multi-factor authentication. Monitor server logs for unusual upload activity or execution attempts of .phar files. Disable PHP execution in directories used for file uploads if possible. Conduct regular security audits and penetration testing focused on file upload functionalities. Finally, ensure backups are current and tested to enable recovery in case of compromise.

Description

Serendipity 2.4.0 contains a remote code execution vulnerability that allows authenticated attackers to upload malicious PHP files with .phar extension. Attackers can upload files with system command payloads to the media upload endpoint and execute arbitrary commands on the server.

References

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