Cyber Resilience

CVE-2025-27145

LowPublic PoC

Published: 25 February 2025

Published
25 February 2025
Modified
19 September 2025
KEV Added
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Patch
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CVSS Score v3.1 3.6 CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
EPSS Score 0.0030 53.5th percentile
Risk Priority 7 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-27145 is a low-severity Cross-site Scripting (CWE-79) vulnerability in 9001 Copyparty. Its CVSS base score is 3.6 (Low).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked in the top 46.5% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability details

copyparty, a portable file server, has a DOM-based cross-site scripting vulnerability in versions prior to 1.16.15. The vulnerability is considered low-risk. By handing someone a maliciously-named file, and then tricking them into dragging the file into copyparty's Web-UI, an attacker…

more

could execute arbitrary javascript with the same privileges as that user. For example, this could give unintended read-access to files owned by that user. The bug is triggered by the drag-drop action itself; it is not necessary to actually initiate the upload. The file must be empty (zero bytes). Note that, as a general-purpose webserver, it is intentionally possible to upload HTML-files with arbitrary javascript in `<script>` tags, which will execute when the file is opened. The difference is that this vulnerability would trigger execution of javascript during the act of uploading, and not when the uploaded file was opened. Version 1.16.15 contains a fix.

CWE(s)
CWE-79CWE-83

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
T1059.007 JavaScript Execution
Adversaries may abuse various implementations of JavaScript for execution.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1204.002 Malicious File Execution
An adversary may rely upon a user opening a malicious file in order to gain execution.
attack.mitre.org →
Why these techniques?

DOM-based XSS via malicious filename in drag-drop to web UI enables JavaScript execution (T1059.007, T1203), triggered by user interaction with malicious file (T1204.002), facilitating local data collection (T1005).

Affected Assets

9001
copyparty
≤ 1.16.15

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

CA-8 Penetration Testing
addresses: CWE-79

Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.

SI-10 Information Input Validation
addresses: CWE-79

Validates web inputs to reject script-related content that could produce XSS.

SI-15 Information Output Filtering
addresses: CWE-79

Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.

References