---
id: CVE-2026-110101
title: >-
  Koillection through 1.8.4 contains a stored cross-site scripting vulnerability
  that allows authenticated users to upload HTML files as Datum file attachments
  lacking MIME restrictions
summary: >-
  Koillection through 1.8.4 contains a stored cross-site scripting vulnerability
  that allows authenticated users to upload HTML files as Datum file attachments
  lacking MIME restrictions. Attackers can upload HTML payloads via POST
  /api/dat…
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N'
cwe:
  - CWE-79
vendor: benjaminjonard
product: Koillection
affected:
  - Koillection <= 1.8.4
published: '2026-10-13'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T23:16:58.910'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-110101'
references:
  - url: >-
      https://github.com/benjaminjonard/koillection/blob/1.8.4/src/Entity/Datum.php#L141-L145
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/benjaminjonard/koillection/blob/1.8.4/src/Service/ImageHandler.php#L43-L50
    label: disclosure@vulncheck.com
  - url: 'https://github.com/benjaminjonard/koillection/issues/1609'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/benjaminjonard/koillection/releases/tag/1.8.4'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/koillection-through-1.8.4-stored-xss-via-datum-file-attachment-uploads
    label: disclosure@vulncheck.com
  - url: 'https://github.com/benjaminjonard/koillection/issues/1609'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
epss: 0.00264
epssPercentile: 0.18398
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-16T22:11:44.598138Z'
ingestedAt: '2026-10-13T17:38:53.184Z'
---

## Overview

Koillection through 1.8.4 contains a stored cross-site scripting vulnerability that allows authenticated users to upload HTML files as Datum file attachments lacking MIME restrictions. Attackers can upload HTML payloads via POST /api/data/{id}/file, served as text/html from public/uploads, executing JavaScript in victims' sessions to perform actions on their behalf.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.