CVE-2003-0121: Clearswift MAILsweeper 4.x allows remote attackers to bypass attachment detection via an attachment that does

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HIGH 7.5DOWNGRADE

CVE-2003-0121 is a high-severity flaw (CVSS 7.5) affecting mailsweeper. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Clearswift MAILsweeper 4.x allows remote attackers to bypass attachment detection via an attachment that does not specify a MIME-Version header field, which is processed by some mail clients.

Why this priority

High severity
Public exploit reference

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

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	3.1% (top 12%)
CISA exploited list	No
Published	2003-03-18
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: clearswift

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2003-03-18 05:00 UTCPublished CVE record published
2026-06-16 22:01 UTCUpdated Record last modified

clearswift mailsweeper DOWNGRADE

Affected: 4.0 · 4.1 · 4.2 · 4.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.0 (Debian / Ubuntu)

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

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

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

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.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: Clearswift MAILsweeper 4.x - MIME Attachment Filter Bypass

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-2003-0121?

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

Is CVE-2003-0121 being exploited?

CVE-2003-0121 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-2003-0121 affect?

CVE-2003-0121 affects mailsweeper. Severity is high (CVSS 7.5). Clearswift MAILsweeper 4.x allows remote attackers to bypass attachment detection via an attachment that does not specify a MIME-Version header field, which is processed by some mail clients.

How urgent is CVE-2003-0121?

Priority 53/100. High severity; Public exploit reference

Related CVEs

CVE-2004-2328 MEDIUM 5.0 DOWNGRADE Clearswift MAILsweeper for SMTP before 4.3_13 allows remote attackers to cause a denial of service (infinite l
CVE-2004-0235 MEDIUM 6.4 DOWNGRADE DOWNGRADE Multiple directory traversal vulnerabilities in LHA 1.14 allow remote attackers or local users to create arbit
CVE-2004-0234 HIGH 10.0 DOWNGRADE DOWNGRADE Multiple stack-based buffer overflows in the get_header function in header.c for LHA 1.14, as used in products
CVE-2004-0162 HIGH 7.5 DOWNGRADE DOWNGRADE Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions
CVE-2004-0161 HIGH 7.5 DOWNGRADE DOWNGRADE Multiple content security gateway and antivirus products allow remote attackers to bypass content restrictions

References

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