CVE-2026-53904: MCO is vulnerable to Account Denial of Service due to improper implementation of password reset functionality

Routine

HIGH 7.1DOWNGRADE

CVE-2026-53904 is a high-severity flaw (CVSS 7.1) affecting mco. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

MCO is vulnerable to Account Denial of Service due to improper implementation of password reset functionality. Each password reset request invalidates previously set password as well as previously issued temporary passwords, furthermore, password resets are not limited in any way. An attacker who provides victim's email and answer to their security question, can successfully initiate the reset process and continuously invalidate credentials, effe

Why this priority

High severity

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

Risk facts

CVSS score	7.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 73%)
CISA exploited list	No
Weakness	CWE-307, CWE-640
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 mco 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 mco || rpm -q mco || mco --version

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

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

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

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

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-2026-53904?

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

Is CVE-2026-53904 being exploited?

CVE-2026-53904 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-2026-53904 affect?

CVE-2026-53904 affects mco. Severity is high (CVSS 7.1). MCO is vulnerable to Account Denial of Service due to improper implementation of password reset functionality. Each password reset request invalidates previously set password as well as previously issued temporary passwords, furthermore, pa

How urgent is CVE-2026-53904?

Priority 32/100. High severity

References

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