CVE-2001-0053: One-byte buffer overflow in replydirname function in BSD-based ftpd allows remote attackers to gain root privi

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HIGH 10.0DOWNGRADEMITIGATEMITIGATE

CVE-2001-0053 is a high-severity flaw (CVSS 10.0) affecting ftpd-bsd, netbsd, openbsd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

One-byte buffer overflow in replydirname function in BSD-based ftpd allows remote attackers to gain root privileges.

Why this priority

Critical severity
EPSS top 3%: very likely to be exploited
Public exploit reference

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

Risk facts

CVSS score	10.0 (High)
EPSS exploit chance	17.9% (top 3%)
CISA exploited list	No
Published	2001-02-12
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: david madore · netbsd · openbsd

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

Am I affected?

Timeline

2001-02-12 05:00 UTCPublished CVE record published
2026-06-16 21:53 UTCUpdated Record last modified

david madore ftpd-bsd DOWNGRADE

Affected: 0.2.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.2.3

1. Check installed version

apt-cache policy ftpd-bsd || rpm -q ftpd-bsd || ftpd-bsd --version

2. No fixed release: DOWNGRADE to a release before 0.2.3 (Debian / Ubuntu)

apt-cache madison ftpd-bsd sudo apt install ftpd-bsd=<VERSION_BEFORE_0.2.3> sudo apt-mark hold ftpd-bsd

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

dnf --showduplicates list ftpd-bsd sudo dnf downgrade ftpd-bsd-<VERSION_BEFORE_0.2.3> sudo dnf versionlock add ftpd-bsd

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.

netbsd netbsd MITIGATE

Affected: 1.4 · 1.4.1 · 1.4.2 · 1.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.4

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

openbsd openbsd MITIGATE

Affected: 2.4 · 2.5 · 2.6 · 2.7 · 2.8

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.4

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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: OpenBSD ftpd 2.6/2.7 - Remote Overflow
Exploit-DB: BSD ftpd 0.3.2 - Single Byte Buffer Overflow

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-2001-0053?

ftpd-bsd: downgrade or apply the listed mitigation; netbsd: mitigate or apply the listed mitigation; openbsd: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2001-0053 being exploited?

CVE-2001-0053 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-2001-0053 affect?

CVE-2001-0053 affects ftpd-bsd, netbsd, openbsd. Severity is high (CVSS 10.0). One-byte buffer overflow in replydirname function in BSD-based ftpd allows remote attackers to gain root privileges.

How urgent is CVE-2001-0053?

Priority 64/100. Critical severity; EPSS top 3%: very likely to be exploited; Public exploit reference

Related CVEs

CVE-2001-0550 HIGH 7.5 DOWNGRADE DOWNGRADE wu-ftpd 2.6.1 allows remote attackers to execute arbitrary commands via a "~{" argument to commands such as CW

References

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