XSS in Mycomplianceoffice Mco
CVE-2026-53907
MCO is vulnerable to Stored Cross‑Site Scripting (XSS) via the application logo upload functionality. An attacker with the ability to change the application logo can upload a crafted SVG file containing malicious JavaScript code that is executed when the logo is rendered or opened. Because vendor contact attempts were unsuccessful, the vulnerability has only been confirmed in version 25.3.3.1 but may also affect other versions.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.002 (13.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 14th percentile — 13.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Mycomplianceoffice Mco — versions 25.3.3.1
- Mycomplianceoffice — versions 25.3.3.1
Weakness classification (CWE)
References
- cert.pl/en/posts/2026/07/CVE-2026-53902 (Third Party Advisory, third-party-advisory)
- mco.mycomplianceoffice.com/ (Product, product)
Frequently asked questions
- What is CVE-2026-53907?
- CVE-2026-53907 is a medium-severity vulnerability in Mycomplianceoffice Mco, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-07-01.
- How severe is CVE-2026-53907?
- Medium severity. CVSS v3 base score is 5.4 out of 10.