CVE-2005-0851: FileZilla FTP server before 0.9.6, when using MODE Z (zlib compression), allows remote attackers to cause a de

Q: How do I fix CVE-2005-0851?

filezilla server: upgrade to 0.9.6. Exact commands for each OS are on this page.

Q: Is CVE-2005-0851 being exploited?

CVE-2005-0851 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2005-0851 affect?

CVE-2005-0851 affects filezilla server. Severity is medium (CVSS 5.0). FileZilla FTP server before 0.9.6, when using MODE Z (zlib compression), allows remote attackers to cause a denial of service (infinite loop) via certain file uploads or directory listings.

Q: How urgent is CVE-2005-0851?

Priority 38/100. No elevated risk signals yet.

Routine

MEDIUM 5.0UPGRADE

CVE-2005-0851 is a medium-severity flaw (CVSS 5.0) affecting filezilla server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

FileZilla FTP server before 0.9.6, when using MODE Z (zlib compression), allows remote attackers to cause a denial of service (infinite loop) via certain file uploads or directory listings.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	2.2% (top 18%)
CISA exploited list	No
Weakness	CWE-835
Published	2005-05-02
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: filezilla-project

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

Am I affected?

Timeline

2005-05-02 04:00 UTCPublished CVE record published
2026-06-16 22:11 UTCUpdated Record last modified

filezilla-project filezilla server UPGRADE

Affected: < 0.9.6

Fixed in: 0.9.6

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy filezilla-server || rpm -q filezilla-server || filezilla-server --version

2. UPGRADE to 0.9.6 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade filezilla-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade filezilla-server

Note

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

Public exploits and detection

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

Nuclei scan template: FileZilla Server < 0.9.6 - DoS via MODE Z Infinite Loop

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-2005-0851?

filezilla server: upgrade to 0.9.6. Exact commands for each OS are on this page.

Is CVE-2005-0851 being exploited?

CVE-2005-0851 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-2005-0851 affect?

CVE-2005-0851 affects filezilla server. Severity is medium (CVSS 5.0). FileZilla FTP server before 0.9.6, when using MODE Z (zlib compression), allows remote attackers to cause a denial of service (infinite loop) via certain file uploads or directory listings.

How urgent is CVE-2005-0851?

Priority 38/100. No elevated risk signals yet.

Software pages

zlib vulnerabilities · FileZilla vulnerabilities

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References

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