CVE-2003-0466: Off-by-one error in the fb_realpath() function, as derived from the realpath function in BSD, may allow attack

Q: How do I fix CVE-2003-0466?

wu ftpd: downgrade or apply the listed mitigation; wu-ftpd: upgrade to newer than 2.6.2; mac os x: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2003-0466 being exploited?

CVE-2003-0466 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-2003-0466 affect?

CVE-2003-0466 affects wu ftpd, wu-ftpd, mac os x. Severity is critical (CVSS 9.8). Off-by-one error in the fb_realpath() function, as derived from the realpath function in BSD, may allow attackers to execute arbitrary code, as demonstrated in wu-ftpd 2.5.0 through 2.6.2 via commands that cause pathnames of length MAXPATHL

Q: How urgent is CVE-2003-0466?

Priority 74/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

This week

CRITICAL 9.8REMOTEWATCHLISTDOWNGRADEUPGRADEMITIGATE

CVE-2003-0466 is a critical-severity flaw (CVSS 9.8) affecting wu ftpd, wu-ftpd, mac os x. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Off-by-one error in the fb_realpath() function, as derived from the realpath function in BSD, may allow attackers to execute arbitrary code, as demonstrated in wu-ftpd 2.5.0 through 2.6.2 via commands that cause pathnames of length MAXPATHLEN+1 to trigger a buffer overflow, including (1) STOR, (2) RETR, (3) APPE, (4) DELE, (5) MKD, (6) RMD, (7) STOU, or (8) RNTO.

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	78.1% (top 1%)
CISA exploited list	No
Weakness	CWE-193
Published	2003-08-27
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: apple · freebsd · netbsd · redhat · wuftpd

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

Am I affected?

Timeline

2003-08-27 04:00 UTCPublished CVE record published
2026-06-16 22:02 UTCUpdated Record last modified

redhat wu ftpd DOWNGRADE

Affected: 2.6.1-16

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.6.1-16

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.6.1-16 (Debian / Ubuntu)

apt-cache madison wu-ftpd sudo apt install wu-ftpd=<VERSION_BEFORE_2.6.1-16> sudo apt-mark hold wu-ftpd

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

dnf --showduplicates list wu-ftpd sudo dnf downgrade wu-ftpd-<VERSION_BEFORE_2.6.1-16> sudo dnf versionlock add wu-ftpd

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.

wuftpd wu-ftpd UPGRADE

Affected: >= 2.5.0 and <= 2.6.2

Fixed in: newer than 2.6.2

Safe to downgrade to: a release before 2.5.0

1. Check installed version

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

2. UPGRADE to newer than 2.6.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade wu-ftpd

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade wu-ftpd

Note

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

3. If no update is available yet, DOWNGRADE to a release before 2.5.0 (Debian / Ubuntu)

apt-cache madison wu-ftpd sudo apt install wu-ftpd=<VERSION_BEFORE_2.5.0> sudo apt-mark hold wu-ftpd

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list wu-ftpd sudo dnf downgrade wu-ftpd-<VERSION_BEFORE_2.5.0> sudo dnf versionlock add wu-ftpd

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.

apple mac os x MITIGATE

Affected: 10.2.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.2.6

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.

apple mac os x server MITIGATE

Affected: 10.2.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.2.6

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.

freebsd freebsd UPGRADE

Affected: >= 4.0 and <= 5.0

Fixed in: newer than 5.0

Safe to downgrade to: a release before 4.0

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.

netbsd netbsd UPGRADE

Affected: >= 1.5 and <= 1.6.1

Fixed in: newer than 1.6.1

Safe to downgrade to: a release before 1.5

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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · rust-agirru · FIXED · 0.2.0-1.fc46 · FEDORA-2026-4d81cb4100 · source

sudo dnf upgrade --advisory=FEDORA-2026-4d81cb4100

Fedora ELN · fuse-sshfs · FIXED · 3.7.6-3.eln159 · FEDORA-2026-bcb7be7c5c · source

sudo dnf upgrade --advisory=FEDORA-2026-bcb7be7c5c

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: FreeBSD 4.8 - 'realpath()' Off-by-One Buffer Overflow
Exploit-DB: WU-FTPD 2.6.2 - Off-by-One Remote Command Execution
Exploit-DB: WU-FTPD 2.6.2 - Remote Command Execution
Exploit-DB: WU-FTPD 2.6.0/2.6.1/2.6.2 - 'realpath()' Off-by-One Buffer Overflow
Exploit-DB: WU-FTPD 2.6.2 - 'realpath()' Off-by-One 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-2003-0466?

wu ftpd: downgrade or apply the listed mitigation; wu-ftpd: upgrade to newer than 2.6.2; mac os x: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2003-0466 being exploited?

CVE-2003-0466 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-2003-0466 affect?

CVE-2003-0466 affects wu ftpd, wu-ftpd, mac os x. Severity is critical (CVSS 9.8). Off-by-one error in the fb_realpath() function, as derived from the realpath function in BSD, may allow attackers to execute arbitrary code, as demonstrated in wu-ftpd 2.5.0 through 2.6.2 via commands that cause pathnames of length MAXPATHL

How urgent is CVE-2003-0466?

Priority 74/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

References

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