CVE-2026-110101: XSS (CVSS 5.4)

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.

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CVSS v3.1 Score

5.4

MEDIUM

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

EPSS — Exploit Prediction

0.0022

Probability of exploitation

0.11%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other References

https://github.com/benjaminjonard/koillection/blob/1.8.4/src/Entity/Datum.php#L141-L145 https://github.com/benjaminjonard/koillection/blob/1.8.4/src/Service/ImageHandler.php#L43-L50 https://github.com/benjaminjonard/koillection/issues/1609 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 https://github.com/benjaminjonard/koillection/issues/1609

Frequently Asked Questions

What is CVE-2026-110101? +

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. It has a CVSS v3.1 base score of 5.4 (MEDIUM).

How severe is CVE-2026-110101? +

CVE-2026-110101 has a CVSS v3.1 score of 5.4 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0022, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-110101? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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