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CVE-2026-20243: A vulnerability in the ALZ file format parser of ClamAV could allow an unauthenticated, remote attacker to cau

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HIGH 7.5REMOTEUPGRADEUPGRADEUPGRADE

CVE-2026-20243 is a high-severity flaw (CVSS 7.5) affecting secure endpoint, secure endpoint, secure endpoint. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

  • High severity
  • Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score7.5 (High)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance0.6% (top 53%)
CISA exploited listNo
WeaknessCWE-120
Published2026-07-01
Last modified2026-10-25
Publisher (CNA): Cisco Systems, Inc. · Vendor: cisco · clamav

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Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

cisco secure endpoint UPGRADE
Affected: < 1.27.2
Fixed in: 1.27.2
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy secure-endpoint || rpm -q secure-endpoint || secure-endpoint --version
2. UPGRADE to 1.27.2 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade secure-endpoint
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade secure-endpoint
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
cisco secure endpoint UPGRADE
Affected: < 1.29.0
Fixed in: 1.29.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy secure-endpoint || rpm -q secure-endpoint || secure-endpoint --version
2. UPGRADE to 1.29.0 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade secure-endpoint
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade secure-endpoint
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
cisco secure endpoint UPGRADE
Affected: < 8.6.2
Fixed in: 8.6.2
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy secure-endpoint || rpm -q secure-endpoint || secure-endpoint --version
2. UPGRADE to 8.6.2 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade secure-endpoint
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade secure-endpoint
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
clamav clamav UPGRADE
Affected: >= 1.4.0 and < 1.4.5 · >= 1.5.0 and < 1.5.3
Fixed in: 1.4.5, 1.5.3
Safe to downgrade to: a release before 1.4.0
1. Check installed version
apt-cache policy clamav || rpm -q clamav || clamav --version
2. UPGRADE to 1.4.5 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade clamav
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade clamav
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 1.4.0 (Debian / Ubuntu)
apt-cache madison clamav sudo apt install clamav=<VERSION_BEFORE_1.4.0> sudo apt-mark hold clamav
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list clamav sudo dnf downgrade clamav-<VERSION_BEFORE_1.4.0> 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-2026-20243?

secure endpoint: upgrade to 1.27.2; secure endpoint: upgrade to 1.29.0; secure endpoint: upgrade to 8.6.2. Exact commands for each OS are on this page.

Is CVE-2026-20243 being exploited?

CVE-2026-20243 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-2026-20243 affect?

CVE-2026-20243 affects secure endpoint, secure endpoint, secure endpoint. Severity is high (CVSS 7.5). A vulnerability in the ALZ file format parser of ClamAV could allow an unauthenticated, remote attacker to cause a DoS condition, or possibly other expanded impacts, resulting from memory corruption on an affected device. This vulnerabil

How urgent is CVE-2026-20243?

Priority 43/100. High severity; Remotely exploitable, no login, no user action

Software pages

Cisco vulnerabilities

Related CVEs

References

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