CVE-2002-0004: Heap corruption vulnerability in the "at" program allows local users to execute arbitrary code via a malformed

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HIGH 7.2WATCHLISTDOWNGRADEDOWNGRADEMITIGATE

CVE-2002-0004 is a high-severity flaw (CVSS 7.2) affecting openlinux server, openlinux workstation, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Heap corruption vulnerability in the "at" program allows local users to execute arbitrary code via a malformed execution time, which causes at to free the same memory twice.

Why this priority

High severity
Public exploit reference
On your watchlist

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

Risk facts

CVSS score	7.2 (High)
EPSS exploit chance	1.3% (top 29%)
CISA exploited list	No
Published	2002-02-27
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: caldera · debian · freebsd · mandrakesoft · netbsd

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

Am I affected?

Timeline

2002-02-27 05:00 UTCPublished CVE record published
2026-06-16 21:56 UTCUpdated Record last modified

caldera openlinux server DOWNGRADE

Affected: 3.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 3.1 (Debian / Ubuntu)

apt-cache madison openlinux-server sudo apt install openlinux-server=<VERSION_BEFORE_3.1> sudo apt-mark hold openlinux-server

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

dnf --showduplicates list openlinux-server sudo dnf downgrade openlinux-server-<VERSION_BEFORE_3.1> sudo dnf versionlock add openlinux-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.

caldera openlinux workstation DOWNGRADE

Affected: 3.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.1

1. Check installed version

apt-cache policy openlinux-workstation || rpm -q openlinux-workstation || openlinux-workstation --version

2. No fixed release: DOWNGRADE to a release before 3.1 (Debian / Ubuntu)

apt-cache madison openlinux-workstation sudo apt install openlinux-workstation=<VERSION_BEFORE_3.1> sudo apt-mark hold openlinux-workstation

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

dnf --showduplicates list openlinux-workstation sudo dnf downgrade openlinux-workstation-<VERSION_BEFORE_3.1> sudo dnf versionlock add openlinux-workstation

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.

debian debian linux MITIGATE

Affected: 2.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.2

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 MITIGATE

Affected: 4.1.1 · 4.2 · 4.3 · 4.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.1.1

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.

mandrakesoft mandrake linux MITIGATE

Affected: 8.0 · 8.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

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 MITIGATE

Affected: 1.5.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.5.2

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: AT 3.1.8 - Formatted Time Heap 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-2002-0004?

openlinux server: downgrade or apply the listed mitigation; openlinux workstation: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2002-0004 being exploited?

CVE-2002-0004 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-2002-0004 affect?

CVE-2002-0004 affects openlinux server, openlinux workstation, debian linux. Severity is high (CVSS 7.2). Heap corruption vulnerability in the "at" program allows local users to execute arbitrary code via a malformed execution time, which causes at to free the same memory twice.

How urgent is CVE-2002-0004?

Priority 53/100. High severity; Public exploit reference; On your watchlist

Software pages

Debian vulnerabilities

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References

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