CVE-2026-4426: A flaw was found in libarchive

Routine

MEDIUM 6.5WATCHLISTMITIGATEMITIGATEDOWNGRADE

CVE-2026-4426 is a medium-severity flaw (CVSS 6.5) affecting libarchive, hardened images, openshift container platform. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A flaw was found in libarchive. An Undefined Behavior vulnerability exists in the zisofs decompression logic, caused by improper validation of a field (`pz_log2_bs`) read from ISO9660 Rock Ridge extensions. A remote attacker can exploit this by supplying a specially crafted ISO file. This can lead to incorrect memory allocation and potential application crashes, resulting in a denial-of-service (DoS) condition.

Why this priority

On your watchlist

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

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 76%)
CISA exploited list	No
Weakness	CWE-1335
Published	2026-03-19
Last modified	2026-09-01

Publisher (CNA): Red Hat, Inc. · Vendor: libarchive · redhat

Last updated 2026-09-01 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-19 15:16 UTCPublished CVE record published
2026-09-01 13:19 UTCUpdated Record last modified

libarchive libarchive MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

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

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

redhat hardened images MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy hardened-images || rpm -q hardened-images || hardened-images --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

redhat openshift container platform DOWNGRADE

Affected: 4.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0

1. Check installed version

apt-cache policy openshift-container-platform || rpm -q openshift-container-platform || openshift-container-platform --version

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

apt-cache madison openshift-container-platform sudo apt install openshift-container-platform=<VERSION_BEFORE_4.0> sudo apt-mark hold openshift-container-platform

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

dnf --showduplicates list openshift-container-platform sudo dnf downgrade openshift-container-platform-<VERSION_BEFORE_4.0> sudo dnf versionlock add openshift-container-platform

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.

redhat enterprise linux MITIGATE

Affected: 6.0 · 7.0 · 8.0 · 9.0 · 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.0

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.

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-2026-4426?

libarchive: mitigate or apply the listed mitigation; hardened images: mitigate or apply the listed mitigation; openshift container platform: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-4426 being exploited?

CVE-2026-4426 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-2026-4426 affect?

CVE-2026-4426 affects libarchive, hardened images, openshift container platform. Severity is medium (CVSS 6.5). A flaw was found in libarchive. An Undefined Behavior vulnerability exists in the zisofs decompression logic, caused by improper validation of a field (`pz_log2_bs`) read from ISO9660 Rock Ridge extensions. A remote attacker can exploit thi

How urgent is CVE-2026-4426?

Priority 34/100. On your watchlist

Software pages

Red Hat OpenShift vulnerabilities

Related CVEs

CVE-2026-5745 MEDIUM 5.5 MITIGATE MITIGATE A flaw was found in libarchive
CVE-2026-5121 HIGH 7.5 MITIGATE MITIGATE A flaw was found in libarchive
CVE-2026-4424 HIGH 7.5 MITIGATE MITIGATE A flaw was found in libarchive

References

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