CVE-2004-1100: Cross-site scripting (XSS) vulnerability in mailpost.exe in MailPost 5.1.1sv, and possibly earlier versions, w

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MEDIUM 6.8DOWNGRADE

CVE-2004-1100 is a medium-severity flaw (CVSS 6.8) affecting mailpost. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cross-site scripting (XSS) vulnerability in mailpost.exe in MailPost 5.1.1sv, and possibly earlier versions, when debug mode is enabled, allows remote attackers to execute arbitrary web script or HTML via the append parameter.

Why this priority

EPSS top 8%: very likely to be exploited
Public exploit reference

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

Risk facts

CVSS score	6.8 (Medium)
EPSS exploit chance	5.1% (top 8%)
CISA exploited list	No
Published	2005-01-10
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: tips

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

Am I affected?

Timeline

2005-01-10 05:00 UTCPublished CVE record published
2026-06-16 22:07 UTCUpdated Record last modified

tips mailpost DOWNGRADE

Affected: 5.1.1sv

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.1.1sv

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 5.1.1sv (Debian / Ubuntu)

apt-cache madison mailpost sudo apt install mailpost=<VERSION_BEFORE_5.1.1sv> sudo apt-mark hold mailpost

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

dnf --showduplicates list mailpost sudo dnf downgrade mailpost-<VERSION_BEFORE_5.1.1sv> sudo dnf versionlock add mailpost

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: TIPS MailPost 5.1.1 - 'APPEND' Cross-Site Scripting

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-2004-1100?

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

Is CVE-2004-1100 being exploited?

CVE-2004-1100 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-2004-1100 affect?

CVE-2004-1100 affects mailpost. Severity is medium (CVSS 6.8). Cross-site scripting (XSS) vulnerability in mailpost.exe in MailPost 5.1.1sv, and possibly earlier versions, when debug mode is enabled, allows remote attackers to execute arbitrary web script or HTML via the append parameter.

How urgent is CVE-2004-1100?

Priority 52/100. EPSS top 8%: very likely to be exploited; Public exploit reference

Related CVEs

CVE-2004-1103 MEDIUM 5.0 DOWNGRADE MailPost 5.1.1sv, and possibly earlier versions, when debug mode is enabled, allows remote attackers to gain s
CVE-2004-1102 MEDIUM 5.0 DOWNGRADE MailPost 5.1.1sv, and possibly earlier versions, displays a different error message depending on whether the r
CVE-2004-1101 MEDIUM 5.8 DOWNGRADE mailpost.exe in MailPost 5.1.1sv, and possibly earlier versions, allows remote attackers to cause a denial of

References

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