# CVE-2026-53908: User Enumeration in MCO

> Attackers can enumerate valid usernames and emails via distinguishable responses in authentication flows, exposing user data.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Jul 2026
- **Updated:** 1 Jul 2026
- **Also known as:** GHSA-59mp-p3m2-6wr7

## What is CVE-2026-53908?

CVE-2026-53908 is a medium-severity vulnerability in MyComplianceOffice MCO, published on 1 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

MCO is vulnerable to User Enumeration through authentication-related functionalities. The application returns distinguishable responses for valid and invalid users during username reminder and password reset operations. An attacker can leverage these differences to enumerate valid usernames and email addresses.

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-204 (Observable Response Discrepancy)

## Which versions are affected by CVE-2026-53908?

It affects 1 product.


Products: Mycomplianceoffice Mycomplianceoffice.

## How do I fix CVE-2026-53908?

No fix has been published for CVE-2026-53908 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-53908 being exploited?

There is no known exploitation of CVE-2026-53908 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-2026-53903](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)
- [CVE-2026-53906](https://insights.sbomify.com/CVE-2026-53906/): Path Disclosure and Path Traversal in MCO (medium 5.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53908 and fix it if it is affected.

What it is: CVE-2026-53908 is a medium-severity vulnerability in MyComplianceOffice MCO, published on 1 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-53908 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-2026-53908/ (Markdown: https://insights.sbomify.com/CVE-2026-53908/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53908
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53908
- OSV: https://osv.dev/vulnerability/CVE-2026-53908

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53908/
Summaries are generated and may contain mistakes; the official description above is the record.