CVE-2007-1673: unzoo.c, as used in multiple products including AMaViS 2.4.1 and earlier, allows remote attackers to cause a d

Q: How do I fix CVE-2007-1673?

amavis: upgrade to newer than 2.4.1; avast antivirus: upgrade to newer than 4.7.980; avast antivirus home: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2007-1673 being exploited?

CVE-2007-1673 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-2007-1673 affect?

CVE-2007-1673 affects amavis, avast antivirus, avast antivirus home. Severity is high (CVSS 7.8). unzoo.c, as used in multiple products including AMaViS 2.4.1 and earlier, allows remote attackers to cause a denial of service (infinite loop) via a ZOO archive with a direntry structure that points to a previous file.

Q: How urgent is CVE-2007-1673?

Priority 54/100. High severity; Public exploit reference

This month

HIGH 7.8UPGRADEUPGRADEDOWNGRADE

CVE-2007-1673 is a high-severity flaw (CVSS 7.8) affecting amavis, avast antivirus, avast antivirus home. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

unzoo.c, as used in multiple products including AMaViS 2.4.1 and earlier, allows remote attackers to cause a denial of service (infinite loop) via a ZOO archive with a direntry structure that points to a previous file.

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
EPSS exploit chance	3.2% (top 12%)
CISA exploited list	No
Weakness	CWE-399
Published	2007-05-09
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: amavis · avast · avira

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

Am I affected?

Timeline

2007-05-09 01:19 UTCPublished CVE record published
2026-06-16 22:38 UTCUpdated Record last modified

amavis amavis UPGRADE

Affected: <= 2.4.1

Fixed in: newer than 2.4.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy amavis || rpm -q amavis || amavis --version

2. UPGRADE to newer than 2.4.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade amavis

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade amavis

Note

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

avast avast antivirus UPGRADE

Affected: <= 4.7.980 · 4.6.394 · 4.7.652 · 4.7.700

Fixed in: newer than 4.7.980

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy avast-antivirus || rpm -q avast-antivirus || avast-antivirus --version

2. UPGRADE to newer than 4.7.980 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade avast-antivirus

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade avast-antivirus

Note

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

avast avast antivirus home DOWNGRADE

Affected: 4.0 · 4.6 · 4.6.652 · 4.6.655 · 4.6.665 · 4.6.691 · 4.7.827 · 4.7.844

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0

1. Check installed version

apt-cache policy avast-antivirus-home || rpm -q avast-antivirus-home || avast-antivirus-home --version

2. No fixed release: DOWNGRADE to a release before 4.0 (Debian / Ubuntu)

apt-cache madison avast-antivirus-home sudo apt install avast-antivirus-home=<VERSION_BEFORE_4.0> sudo apt-mark hold avast-antivirus-home

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

dnf --showduplicates list avast-antivirus-home sudo dnf downgrade avast-antivirus-home-<VERSION_BEFORE_4.0> sudo dnf versionlock add avast-antivirus-home

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.

avast avast antivirus professional DOWNGRADE

Affected: 4.0 · 4.6 · 4.6.603 · 4.6.652 · 4.6.665 · 4.6.691 · 4.7.827 · 4.7.844

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0

1. Check installed version

apt-cache policy avast-antivirus-professional || rpm -q avast-antivirus-professional || avast-antivirus-professional --version

2. No fixed release: DOWNGRADE to a release before 4.0 (Debian / Ubuntu)

apt-cache madison avast-antivirus-professional sudo apt install avast-antivirus-professional=<VERSION_BEFORE_4.0> sudo apt-mark hold avast-antivirus-professional

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

dnf --showduplicates list avast-antivirus-professional sudo dnf downgrade avast-antivirus-professional-<VERSION_BEFORE_4.0> sudo dnf versionlock add avast-antivirus-professional

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.

avira antivir DOWNGRADE

Affected: all versions · 6.35.00.00 · 7.04.00.23

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.35.00.00

1. Check installed version

apt-cache policy antivir || rpm -q antivir || antivir --version

2. No fixed release: DOWNGRADE to a release before 6.35.00.00 (Debian / Ubuntu)

apt-cache madison antivir sudo apt install antivir=<VERSION_BEFORE_6.35.00.00> sudo apt-mark hold antivir

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

dnf --showduplicates list antivir sudo dnf downgrade antivir-<VERSION_BEFORE_6.35.00.00> sudo dnf versionlock add antivir

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.

avira antivir personal UPGRADE

Affected: all versions · <= 7.3.0.5 · 7

Fixed in: newer than 7.3.0.5

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy antivir-personal || rpm -q antivir-personal || antivir-personal --version

2. UPGRADE to newer than 7.3.0.5 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade antivir-personal

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade antivir-personal

Note

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

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-2007-1673?

amavis: upgrade to newer than 2.4.1; avast antivirus: upgrade to newer than 4.7.980; avast antivirus home: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2007-1673 being exploited?

CVE-2007-1673 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-2007-1673 affect?

CVE-2007-1673 affects amavis, avast antivirus, avast antivirus home. Severity is high (CVSS 7.8). unzoo.c, as used in multiple products including AMaViS 2.4.1 and earlier, allows remote attackers to cause a denial of service (infinite loop) via a ZOO archive with a direntry structure that points to a previous file.

How urgent is CVE-2007-1673?

Priority 54/100. High severity; Public exploit reference

Related CVEs

CVE-2007-1669 HIGH 7.8 UPGRADE zoo decoder 2.10 (zoo-2.10), as used in multiple products including (1) Barracuda Spam Firewall 3.4 and later

References

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