CVE-2026-53903: MCO is vulnerable to an Insecure Direct Object Reference (IDOR) vulnerability in the /customer/servlet/mco/web

Routine

HIGH 8.1DOWNGRADE

CVE-2026-53903 is a high-severity flaw (CVSS 8.1) affecting mycomplianceoffice. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

MCO is vulnerable to an Insecure Direct Object Reference (IDOR) vulnerability in the /customer/servlet/mco/webapi/trading-document/fetchPdfStatement endpoint. The application does not properly validate whether an authenticated user is authorized to access a requested document, allowing direct retrieval based on a user-supplied identifier. An attacker can access trading documents belonging to other users by providing a valid document ID. Although

Why this priority

High severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 65%)
CISA exploited list	No
Weakness	CWE-639
Published	2026-07-01
Last modified	2026-10-25

Publisher (CNA): CERT.PL · Vendor: mycomplianceoffice

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-01 13:17 UTCPublished CVE record published
2026-10-25 17:10 UTCUpdated Record last modified

mycomplianceoffice mycomplianceoffice DOWNGRADE

Affected: 25.3.3.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 25.3.3.1

1. Check installed version

apt-cache policy mycomplianceoffice || rpm -q mycomplianceoffice || mycomplianceoffice --version

2. No fixed release: DOWNGRADE to a release before 25.3.3.1 (Debian / Ubuntu)

apt-cache madison mycomplianceoffice sudo apt install mycomplianceoffice=<VERSION_BEFORE_25.3.3.1> sudo apt-mark hold mycomplianceoffice

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list mycomplianceoffice sudo dnf downgrade mycomplianceoffice-<VERSION_BEFORE_25.3.3.1> sudo dnf versionlock add mycomplianceoffice

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-53903?

mycomplianceoffice: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-53903 being exploited?

CVE-2026-53903 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-53903 affect?

CVE-2026-53903 affects mycomplianceoffice. Severity is high (CVSS 8.1). MCO is vulnerable to an Insecure Direct Object Reference (IDOR) vulnerability in the /customer/servlet/mco/webapi/trading-document/fetchPdfStatement endpoint. The application does not properly validate whether an authenticated user is autho

How urgent is CVE-2026-53903?

Priority 37/100. High severity

Related CVEs

CVE-2026-53906 HIGH 8.2 DOWNGRADE MCO is vulnerable to Path Disclosure and Path Traversal in file handling functionality related to data export
CVE-2026-53905 HIGH 7.1 DOWNGRADE MCO does not properly enforce authorization checks in the /customer/servlet/mco/webapi/admin-view-hierarchy/ge
CVE-2026-53909 MEDIUM 6.5 DOWNGRADE MCO does not correctly validate types of uploaded files
CVE-2026-53902 MEDIUM 6.5 DOWNGRADE MCO does not properly enforce authorization checks in the /customer/servlet/mco/webapi/profile-sections/group-
CVE-2026-53907 MEDIUM 5.4 DOWNGRADE MCO is vulnerable to Stored Cross‑Site Scripting (XSS) via the application logo upload functionality

References

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