# CVE-2026-53907: Stored Cross‑Site Scripting in MCO

> An attacker can execute arbitrary JavaScript in the MCO web application by uploading a malicious SVG logo, potentially compromising user sessions.

- **Severity:** Medium 4.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 1 Jul 2026
- **Updated:** 1 Jul 2026
- **Also known as:** GHSA-r38x-66p9-p239

## What is CVE-2026-53907?

CVE-2026-53907 is a medium-severity cross-site scripting vulnerability in MyComplianceOffice MCO, published on 1 Jul 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

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.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-53907?

It affects 1 product.


Products: Mycomplianceoffice Mycomplianceoffice.

## How do I fix CVE-2026-53907?

No fix has been published for CVE-2026-53907 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-53907 being exploited?

There is no known exploitation of CVE-2026-53907 in the wild and no public exploit code.

## Other vulnerabilities in MyComplianceOffice MCO

- [CVE-2026-53902](https://insights.sbomify.com/CVE-2026-53902/): Privilege Escalation in MCO (high 7.1)
- [CVE-2026-53908](https://insights.sbomify.com/CVE-2026-53908/): User Enumeration in MCO (medium 6.9)
- [CVE-2026-53903](https://insights.sbomify.com/CVE-2026-53903/): Insecure Direct Object Reference in MCO (medium 5.3)
- [CVE-2026-53905](https://insights.sbomify.com/CVE-2026-53905/): Unauthorized Access to Administrator ACL View in MCO (medium 5.3)
- [CVE-2026-53909](https://insights.sbomify.com/CVE-2026-53909/): Arbitrary File Upload in MCO (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53907 and fix it if it is affected.

What it is: CVE-2026-53907 is a medium-severity cross-site scripting vulnerability in MyComplianceOffice MCO, published on 1 Jul 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-53907 in the wild and no public exploit code.

Affected product: MyComplianceOffice MCO. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-53907/ (Markdown: https://insights.sbomify.com/CVE-2026-53907/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53907
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53907
- OSV: https://osv.dev/vulnerability/CVE-2026-53907

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-53907/
Summaries are generated and may contain mistakes; the official description above is the record.