# CVE-2019-18952: SibSoft Xfilesharing - Arbitrary File Upload

> Live exploitation tracking for CVE-2019-18952 by the CrowdSec Live Exploit Tracker, built from real-world attack data crowdsourced from CrowdSec's global network.

Page: https://tracker.crowdsec.net/cves/CVE-2019-18952

## Key facts

- **Exploitation phase:** Background Noise. Continuous low-level scanning or exploitation attempts are observed, mostly opportunistic and automated.
- **CVSS score:** 9.8
- **Public exploit available:** Yes
- **Affected products:** SibSoft Xfilesharing
- **Weaknesses:** CWE-434 (Unrestricted Upload of File with Dangerous Type)
- **Tags:** file_sharing

## Description

SibSoft Xfilesharing through 2.5.1 allows cgi-bin/up.cgi arbitrary file upload. This can be combined with CVE-2019-18951 to achieve remote code execution via a .html file, containing short codes, that is served over HTTP.

## CrowdSec analysis

[CVE-2019-18952](https://euvd.enisa.europa.eu/vulnerability/CVE-2019-18952) is a critical vulnerability in SibSoft Xfilesharing up to version 2.5.1 that allows arbitrary file uploads via the cgi-bin/up.cgi endpoint. Attackers can exploit this flaw to upload malicious files, and when combined with CVE-2019-18951, it can lead to remote code execution by serving crafted .html files over HTTP. This vulnerability poses a severe risk, enabling threat actors to fully compromise affected systems.

CrowdSec has been tracking this vulnerability and its exploits since 15th of October 2025.

Data from the CrowdSec community indicates that exploitation of CVE-2019-18952 is highly selective and intelligence-driven. Threat actors use advanced reconnaissance and carefully choose their targets, often as part of sophisticated campaigns or advanced persistent threat operations.
Data from the CrowdSec community also indicates a gradual decrease in attacks targeting CVE-2019-18952. While still present in the wild, exploitation levels have dropped noticeably week-over-week. This may signal that the vulnerability is becoming less relevant or that defenses are improving fast enough for attackers to lose interest.

Attackers exploit the `/cgi-bin/up.cgi` endpoint to upload arbitrary files, often with executable extensions, enabling remote code execution when the uploaded file is accessed via `/cgi-bin/temp/`.

## Timeline

- 2019-11-13: CVE Published. CVE-2019-18952 is published to NVD.
- 2025-10-15: Rule Released. CrowdSec releases a rule to detect CVE-2019-18952 exploitation attempts against the CrowdSec Network.
- 2025-10-16: CrowdSec First Seen. CrowdSec observes in-the-wild exploitation of CVE-2019-18952 for the first time.

## References

- https://gist.github.com/pak0s/af9f640170aed335fdf6d110d468dbce
- http://packetstormsecurity.com/files/155324/Xfilesharing-2.5.1-Local-File-Inclusion-Shell-Upload.html
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2019/CVE-2019-18952.yaml

## Live exploitation data

The [Live Exploit Tracker page](https://tracker.crowdsec.net/cves/CVE-2019-18952) follows observed exploitation activity for CVE-2019-18952. [Request an API key](https://tracker.crowdsec.net/request-api-key) for full access to its exploitation timeline, attacking IP addresses and blocklists.