CVE-2025-27145 | copyparty renders unsanitized filenames as HTML when user uploads empty files

Exp

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 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.

Published: 2025-02-25 Last update: 2025-09-19 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2025-27145 is rated Exploit Available (50/100): CVSS Low severity, with low exploitation likelihood (EPSS 0.43%). Core evidence: 1 public exploit reference(s) are indexed (Exploit-DB). Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2025-27145

EDB-ID Source Kind Published Link
nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2025-27145

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.30% 0.43% +0.13%
2 2026-04-07 0.21% 0.30% +0.08%
3 2026-04-05 0.21%

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-27145

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
3.6 3.1 LOW
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
1.0 2.5 [email protected]
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
2.8 2.7 [email protected]

Weakness enumeration for CVE-2025-27145

GitHub Security Advisory for CVE-2025-27145

GHSA-m2jw-cj8v-937r · Severity: low · Ecosystem: pip — copyparty renders unsanitized filenames as HTML when user uploads empty files

Affected software / configurations for CVE-2025-27145

Vendor Product Version Raw CPE
9001 copyparty < 1.16.15 cpe:2.3:a:9001:copyparty:*:*:*:*:*:*:*:*

References for CVE-2025-27145

cvelogic Threat Intelligence