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NVD / CVE Program· CNA GitHub_M

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

Noroxi assessment

Priority: Monitor (action score 24/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.46% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: copyparty (PyPI) 1.16.15.
  • Severity is disputed: the assigning authority (CNA) scores it 3.6, NVD 6.1.

Low priority for now. Upgrade to copyparty (PyPI) 1.16.15 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 6.1 · v3.1—No exploit Fix available
Published
Feb 24, 2025
Updated
Jun 17, 2026
EPSS
0.4% · 40th percentile

Report tools

JSON

Action score

24

Monitor

Low priority for now.

CVSS
24 / 40 · 6.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
6.1
CNA · GitHub_M
3.6
2.5 point gap

CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
9001copyparty

Limit the impact of XSS

This is a cross-site scripting (XSS) vulnerability. A well-configured Content-Security-Policy doesn't fix it, but greatly reduces its impact. Check your site's CSP and other security headers for free.

Check security headers

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • 9001 copypartybefore 1.16.15

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • 9001 copyparty

    • < 1.16.15affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
PyPIcopypartybefore 1.16.151.16.15

Same product

9001: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-37474Path traversal in copyparty
    43Plan
  • CVE-2023-41471Cross Site Scripting vulnerability in copyparty before 1.9.2 allows a local attacker to execute arbitrary code via a crafted payload to the
    31Monitor
  • CVE-2025-54796Copyparty is vulnerable to Regex Denial of Service (ReDoS) attacks through "Recent Uploads" page
    30Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2023-38501Jul 25, 2023 · copyparty vulnerable to reflected cross-site scripting via k304 parameter
    27Monitor
  • Later →CVE-2025-54423Jul 28, 2025 · copyparty has a DOM-Based XSS vulnerability when displaying multimedia metadata
    24Monitor
  • Later →CVE-2025-54589Jul 31, 2025 · copyparty Reflected XSS via Filter Parameter
    25Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
PyPI:copyparty1.16.15Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2023-41471186 days apartCross Site Scripting vulnerability in copyparty before 1.9.2 allows a local attacker to execute arbitrary code via a crafted payload to the
    31Monitor
  • CVE-2025-54589157 days apartcopyparty Reflected XSS via Filter Parameter
    25Monitor
  • CVE-2025-54423154 days apartcopyparty has a DOM-Based XSS vulnerability when displaying multimedia metadata
    24Monitor
  • CVE-2026-27948366 days apartCopyparty vulnerable to eflected cross-site scripting via setck parameter
    24Monitor
  • CVE-2026-30974379 days apartCopyparty volflag `nohtml` did not block javascript in svg files
    21Monitor
  • CVE-2026-32109380 days apartCopyparty has unexpected JavaScript execution via crafted URL to folder with `.prologue.html`
    17Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
low · data or configuration can be modified
Availability
none

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Changed
Confidentiality impact
Low
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

nvd-primary

Root cause

User content is inserted into the page as HTML. The browser interprets the content as code rather than data.

The bug in code

The whole CWE-79 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
commentEl.innerHTML = comment.body;

Fixed

ts
commentEl.textContent = comment.body;

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records