Vulnerability · Published Oct 13, 2026 · Assigned by VulnCheck

CVE-2026-110101Koillection through 1.8.4 Stored XSS via Datum File Attachment Uploads

Medium 5.4

In plain English

A medium-severity cross-site scripting in Koillection from benjaminjonard. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities).

Severity (CVSS 3.1)5.4Medium

Exploit odds (30 days)0.3%top 81.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
benjaminjonard	Koillection	0 – through 1.8.4

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

References

https://github.com/benjaminjonard/koillection/issues/1609 issue-tracking, technical-description
https://github.com/benjaminjonard/koillection/blob/1.8.4/src/Service/ImageHandler.php#L43-L50 technical-description
https://github.com/benjaminjonard/koillection/blob/1.8.4/src/Entity/Datum.php#L141-L145 technical-description
Koillection 1.8.4 Release Notes release-notes
VulnCheck Advisory: Koillection through 1.8.4 Stored XSS via Datum File Attachment Uploads third-party-advisory