CVE-2023-22278: m-FILTER prior to Ver.5.70R01 (Ver.5 Series) and m-FILTER prior to Ver.4.87R04 (Ver.4 Series) allows a remote

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2023-22278 is a medium-severity flaw (CVSS 5.3) affecting m-filter. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

m-FILTER prior to Ver.5.70R01 (Ver.5 Series) and m-FILTER prior to Ver.4.87R04 (Ver.4 Series) allows a remote unauthenticated attacker to bypass authentication and send users' unintended email when email is being sent under the certain conditions. The attacks exploiting this vulnerability have been observed.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 46%)
CISA exploited list	No
Weakness	CWE-287
Published	2023-01-17
Last modified	2026-06-17

Publisher (CNA): JPCERT/CC · Vendor: daj

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-01-17 10:15 UTCPublished CVE record published
2026-06-17 05:34 UTCUpdated Record last modified

daj m-filter UPGRADE

Affected: >= 4.0 and < 4.87r04 · >= 5.0 and < 5.70r01

Fixed in: 4.87r04, 5.70r01

Safe to downgrade to: a release before 4.0

1. Check installed version

apt-cache policy m-filter || rpm -q m-filter || m-filter --version

2. UPGRADE to 4.87r04 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade m-filter

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade m-filter

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 4.0 (Debian / Ubuntu)

apt-cache madison m-filter sudo apt install m-filter=<VERSION_BEFORE_4.0> sudo apt-mark hold m-filter

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list m-filter sudo dnf downgrade m-filter-<VERSION_BEFORE_4.0> sudo dnf versionlock add m-filter

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-2023-22278?

m-filter: upgrade to 4.87r04, 5.70r01. Exact commands for each OS are on this page.

Is CVE-2023-22278 being exploited?

CVE-2023-22278 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-2023-22278 affect?

CVE-2023-22278 affects m-filter. Severity is medium (CVSS 5.3). m-FILTER prior to Ver.5.70R01 (Ver.5 Series) and m-FILTER prior to Ver.4.87R04 (Ver.4 Series) allows a remote unauthenticated attacker to bypass authentication and send users' unintended email when email is being sent under the certain cond

How urgent is CVE-2023-22278?

Priority 37/100. Remotely exploitable, no login, no user action

References

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