CVE-2026-20347: A vulnerability in the Mach-O file format parser of ClamAV could allow an unauthenticated, remote attacker to

This month

HIGH 7.5REMOTE

CVE-2026-20347 is a high-severity flaw (CVSS 7.5) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability in the Mach-O file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition or possibly other expanded impacts as a result of memory corruption on an affected device. This vulnerability is due to improper boundary checks for content in Mach-O files during scanning, which may result in an out-of-bounds buffer read. An attacker could exploit this vulnerability by submitting a crafted M

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 61%)
CISA exploited list	No
Weakness	CWE-125
Published	2026-08-07
Last modified	2026-10-23

Publisher (CNA): Cisco Systems, Inc.

Last updated 2026-10-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-08-07 17:17 UTCPublished CVE record published
2026-10-23 20:10 UTCUpdated Record last modified

Exact fixes by distribution

Fedora 46 · kwin-zones · FIXED · 1.0.13-1.fc46 · FEDORA-2026-95888f332b · source

sudo dnf upgrade --advisory=FEDORA-2026-95888f332b

Fedora ELN · nginx-mod-brotli · FIXED · 1.0.0~rc-16.eln159 · FEDORA-2026-501a6a8273 · source

sudo dnf upgrade --advisory=FEDORA-2026-501a6a8273

Ubuntu 22.04 · clamav · FIXED · 1.5.4+dfsg-0ubuntu0.22.04.1

sudo apt update && sudo apt install --only-upgrade clamav dpkg --compare-versions "$(dpkg-query -W -f='${Version}' clamav)" ge "1.5.4+dfsg-0ubuntu0.22.04.1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.04 · clamav · FIXED · 1.5.4+dfsg-0ubuntu0.24.04.1

sudo apt update && sudo apt install --only-upgrade clamav dpkg --compare-versions "$(dpkg-query -W -f='${Version}' clamav)" ge "1.5.4+dfsg-0ubuntu0.24.04.1" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · clamav · FIXED · 1.4.6+dfsg-0+deb12u1

sudo apt update && sudo apt install --only-upgrade clamav dpkg --compare-versions "$(dpkg-query -W -f='${Version}' clamav)" ge "1.4.6+dfsg-0+deb12u1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · clamav · NO FIX YET

Alpine 3.24 · clamav · FIXED · clamav-1.4.6-r0

apk add --upgrade clamav apk info -v clamav

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-2116 · source

sudo dnf update --advisory=ALAS2023-2026-2116

Amazon Linux 2 · see advisory · FIXED · ALAS2-2026-3894 · source

sudo yum update --advisory=ALAS2-2026-3894

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-Wuuv

Advisories and coverage

Official advisories

Amazon Linux 2 ALAS: ALAS2-2026-3894 (important): clamav1.4 2026-08-31

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-2026-20347?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-20347 being exploited?

CVE-2026-20347 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-2026-20347 affect?

CVE-2026-20347 affects affected software. Severity is high (CVSS 7.5). A vulnerability in the Mach-O file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition or possibly other expanded impacts as a result of memory corruption on an affected device. This vuln

How urgent is CVE-2026-20347?

Priority 41/100. High severity; Remotely exploitable, no login, no user action

References

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