CVE-2005-1923: The ENSURE_BITS macro in mszipd.c for Clam AntiVirus (ClamAV) 0.83, and other versions vefore 0.86, allows rem

Routine

LOW 2.6DOWNGRADE

CVE-2005-1923 is a low-severity flaw (CVSS 2.6) affecting clamav. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The ENSURE_BITS macro in mszipd.c for Clam AntiVirus (ClamAV) 0.83, and other versions vefore 0.86, allows remote attackers to cause a denial of service (CPU consumption by infinite loop) via a cabinet (CAB) file with the cffile_FolderOffset field set to 0xff, which causes a zero-length read.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	2.6 (Low)
EPSS exploit chance	1.6% (top 24%)
CISA exploited list	No
Published	2005-07-05
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: clam anti-virus

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

Am I affected?

Timeline

2005-07-05 04:00 UTCPublished CVE record published
2026-06-16 22:13 UTCUpdated Record last modified

clam anti-virus clamav DOWNGRADE

Affected: 0.83 · 0.84_rc1 · 0.84_rc2 · 0.85 · 0.85.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.83

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.83 (Debian / Ubuntu)

apt-cache madison clamav sudo apt install clamav=<VERSION_BEFORE_0.83> sudo apt-mark hold clamav

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

dnf --showduplicates list clamav sudo dnf downgrade clamav-<VERSION_BEFORE_0.83> sudo dnf versionlock add clamav

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.

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-2005-1923?

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

Is CVE-2005-1923 being exploited?

CVE-2005-1923 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-2005-1923 affect?

CVE-2005-1923 affects clamav. Severity is low (CVSS 2.6). The ENSURE_BITS macro in mszipd.c for Clam AntiVirus (ClamAV) 0.83, and other versions vefore 0.86, allows remote attackers to cause a denial of service (CPU consumption by infinite loop) via a cabinet (CAB) file with the cffile_FolderOffse

How urgent is CVE-2005-1923?

Priority 28/100. No elevated risk signals yet.

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References

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