CVE-2006-6558: Crob FTP Server 3.6.1 b.263 allows remote attackers to cause a denial of service via a long series of "?A" seq

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MEDIUM 5.0DOWNGRADE

CVE-2006-6558 is a medium-severity flaw (CVSS 5.0) affecting crob ftp server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Crob FTP Server 3.6.1 b.263 allows remote attackers to cause a denial of service via a long series of "?A" sequences in the (1) LIST and possibly (2) NLST command.

Why this priority

EPSS top 6%: very likely to be exploited
Public exploit reference

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

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	6.4% (top 6%)
CISA exploited list	No
Published	2006-12-14
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: crob

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

Am I affected?

Timeline

2006-12-14 18:28 UTCPublished CVE record published
2026-06-16 22:33 UTCUpdated Record last modified

crob crob ftp server DOWNGRADE

Affected: 3.6.1_b.263

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.6.1_b.263

1. Check installed version

apt-cache policy crob-ftp-server || rpm -q crob-ftp-server || crob-ftp-server --version

2. No fixed release: DOWNGRADE to a release before 3.6.1_b.263 (Debian / Ubuntu)

apt-cache madison crob-ftp-server sudo apt install crob-ftp-server=<VERSION_BEFORE_3.6.1_b.263> sudo apt-mark hold crob-ftp-server

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

dnf --showduplicates list crob-ftp-server sudo dnf downgrade crob-ftp-server-<VERSION_BEFORE_3.6.1_b.263> sudo dnf versionlock add crob-ftp-server

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: Crob FTP Server 3.6.1 build 263 - 'LIST/NLST' Denial of Service

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-2006-6558?

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

Is CVE-2006-6558 being exploited?

CVE-2006-6558 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-2006-6558 affect?

CVE-2006-6558 affects crob ftp server. Severity is medium (CVSS 5.0). Crob FTP Server 3.6.1 b.263 allows remote attackers to cause a denial of service via a long series of "?A" sequences in the (1) LIST and possibly (2) NLST command.

How urgent is CVE-2006-6558?

Priority 46/100. EPSS top 6%: very likely to be exploited; Public exploit reference

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References

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