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Full vulnerability report · 2026
CVE-2026-4426High confidence

Libarchive: libarchive: denial of service via malformed iso file processing

Red Hat · Red Hat Hardened Images

Official source article: Red Hat RHSA-2026:8944 ↗. Check the applicable product and release in the original source.

6.5MediumCVSS 3.1
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 0.56% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Red Hat Red Hat Hardened Images and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Distribution package intelligence

Release-specific package status

Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

5 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcelibarchiveVendor fix publishedDebian records a fixed source-package version for this release.3.7.4-4+deb13u1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourcelibarchiveVendor fix publishedDebian records a fixed source-package version for this release.3.6.2-1+deb12u4Debian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourcelibarchiveVendor fix publishedDebian records a fixed source-package version for this release.3.8.7-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourcelibarchiveVendor fix publishedDebian records a fixed source-package version for this release.3.8.7-1Debian Security Tracker ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archivelibarchiveVendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.3.7.2-2ubuntu0.7Canonical Ubuntu Security ↗Source updated 5 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-4426 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitylibarchive: libarchive: Denial of Service via malformed ISO file processing
22 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • bsdtar as a component of Red Hat Enterprise Linux 10
  • libarchive as a component of Red Hat Enterprise Linux 10
  • libarchive-devel as a component of Red Hat Enterprise Linux 10
  • libarchive.src as a component of Red Hat Enterprise Linux 10
  • libarchive as a component of Red Hat Enterprise Linux 6
  • libarchive-devel as a component of Red Hat Enterprise Linux 6
  • libarchive.src as a component of Red Hat Enterprise Linux 6
  • bsdcpio as a component of Red Hat Enterprise Linux 7
  • bsdtar as a component of Red Hat Enterprise Linux 7
  • libarchive as a component of Red Hat Enterprise Linux 7
  • libarchive-devel as a component of Red Hat Enterprise Linux 7
  • libarchive.src as a component of Red Hat Enterprise Linux 7
Summary
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.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-13099

No EUVD known-exploited evidence

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.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
6.5 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
01

What, why and how

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.

What

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

An integer value is specified to be shifted by a negative amount or an amount greater than or equal to the number of bits contained in the value causing an unexpected or indeterminate result.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may disrupt the affected service.

What

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

An integer value is specified to be shifted by a negative amount or an amount greater than or equal to the number of bits contained in the value causing an unexpected or indeterminate result.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may disrupt the affected service.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Incorrect Bitwise Shift of Integer → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
Required interaction required
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-1335 ↗

CWE-1335: Incorrect Bitwise Shift of Integer. An integer value is specified to be shifted by a negative amount or an amount greater than or equal to the number of bits contained in the value causing an unexpected or indeterminate result.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedDenial of serviceCWE-1335
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-13099Official EUVD mapping

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.

Official EUVD record ↗
BSI · German · WID-SEC-2026-0803libarchive: Mehrere Schwachstellen ermöglichen Offenlegung von Informationen und DoS

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in libarchive ausnutzen, um Informationen offenzulegen und um einen Denial-of-Service-Zustand zu erzeugen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260325Security Bulletin 25 Mar 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 25 Mar 2026, published on 25 March 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-013084libarchive等の複数ベンダの製品における整数への不適切なビットシフトに関する脆弱性

libarchiveに脆弱性が発見されました。zisofsの解凍ロジックに未定義の動作を引き起こす脆弱性が存在し、これはISO9660 Rock Ridge拡張から読み取られるフィールド（`pz_log2_bs`）の不適切な検証によって生じます。リモートの攻撃者は、特別に細工されたISOファイルを提供することでこの脆弱性を悪用できます。その結果、不正なメモリ割り当てが発生し、アプリケーションがクラッシュしてサービス拒否（DoS）状態を招く可能性があります。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
Action
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 19 Mar 2026 · Last source change 1 Sept 2026, 11:59 UTC · CWE-1335 · Incorrect Bitwise Shift of Integer

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-13099
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    bsdtar as a component of Red Hat Enterprise Linux 10; libarchive as a component of Red Hat Enterprise Linux 10; libarchive-devel as a component of Red Hat Enterprise Linux 10; libarchive.src as a component of Red Hat Enterprise Linux 10; libarchive as a component of Red Hat Enterprise Linux 6; libarchive-devel as a component of Red Hat Enterprise Linux 6; libarchive.src as a component of Red Hat Enterprise Linux 6; bsdcpio as a component of Red Hat Enterprise Linux 7; bsdtar as a component of Red Hat Enterprise Linux 7; libarchive as a component of Red Hat Enterprise Linux 7; libarchive-devel as a component of Red Hat Enterprise Linux 7; libarchive.src as a component of Red Hat Enterprise Linux 7; bsdtar as a component of Red Hat Enterprise Linux 8; libarchive as a component of Red Hat Enterprise Linux 8; libarchive-devel as a component of Red Hat Enterprise Linux 8; libarchive.src as a component of Red Hat Enterprise Linux 8; bsdtar as a component of Red Hat Enterprise Linux 9; libarchive as a component of Red Hat Enterprise Linux 9; libarchive-devel as a component of Red Hat Enterprise Linux 9; libarchive.src as a component of Red Hat Enterprise Linux 9; openshift/ose-rhel-coreos-9 as a component of Red Hat OpenShift Container Platform 4 · Fixed: libarchive-main@aarch64 as a component of Red Hat Hardened Images; libarchive-main@src as a component of Red Hat Hardened Images; libarchive-main@x86_64 as a component of Red Hat Hardened Images
    After
    bsdtar as a component of Red Hat Enterprise Linux 10; libarchive as a component of Red Hat Enterprise Linux 10; libarchive-devel as a component of Red Hat Enterprise Linux 10; libarchive.src as a component of Red Hat Enterprise Linux 10; libarchive as a component of Red Hat Enterprise Linux 6; libarchive-devel as a component of Red Hat Enterprise Linux 6; libarchive.src as a component of Red Hat Enterprise Linux 6; bsdcpio as a component of Red Hat Enterprise Linux 7; bsdtar as a component of Red Hat Enterprise Linux 7; libarchive as a component of Red Hat Enterprise Linux 7; libarchive-devel as a component of Red Hat Enterprise Linux 7; libarchive.src as a component of Red Hat Enterprise Linux 7; bsdtar as a component of Red Hat Enterprise Linux 8; libarchive as a component of Red Hat Enterprise Linux 8; libarchive-devel as a component of Red Hat Enterprise Linux 8; libarchive.src as a component of Red Hat Enterprise Linux 8; bsdtar as a component of Red Hat Enterprise Linux 9; libarchive as a component of Red Hat Enterprise Linux 9; libarchive-devel as a component of Red Hat Enterprise Linux 9; libarchive.src as a component of Red Hat Enterprise Linux 9; openshift/ose-rhel-coreos-8 as a component of Red Hat OpenShift Container Platform 4; openshift/ose-rhel-coreos-9 as a component of Red Hat OpenShift Container Platform 4 · Fixed: libarchive-main@aarch64 as a component of Red Hat Hardened Images; libarchive-main@src as a component of Red Hat Hardened Images; libarchive-main@x86_64 as a component of Red Hat Hardened Images
    Red Hat Product Security ↗
  2. Affected versionsThe structured affected or fixed version information changed.
    Before
    See the vendor and CVE records for the affected range. · Fixed: 3.8.7-1.hum1 < *
    After
    See the vendor and CVE records for the affected range. · Fixed: Red Hat Hardened Images: 3.8.7-1.hum1 < *
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-13099↗Vendor CSAF · Red Hat Product Security↗Patch or update reference↗CVE authority or vendor reference · Red Hat RHSA-2026:8944↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-4426 · cve.blacktree.nl