Libarchive: a null pointer dereference vulnerability exists in the acl parser of libarchive
Red Hat · Red Hat Hardened Images
5.5MediumCVSS 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
Distribution package intelligence
Ubuntu vendor package status
Canonical’s release and source-package findings are shown separately from local repository availability.
1 package state
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.
Ubuntu release
Source package
Vendor state
Fixed version
Evidence
Ubuntu 24.04 LTSnoble · standard archive
libarchive
Vendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.
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-2026-5745 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitylibarchive: A NULL pointer dereference vulnerability exists in the ACL parser of libarchive
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. A NULL pointer dereference vulnerability exists in the ACL parsing logic, specifically within the archive_acl_from_text_nl() function. When processing a malformed ACL string (such as a bare "d" or "default" tag without subsequent fields), the function fails to perform adequate validation before advancing the pointer. An attacker can exploit this by providing a maliciously crafted archive, causing an application utilizing the libarchive API (such as bsdtar) to crash, resulting in a Denial of Service (DoS).
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.
Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.
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-2026-19705
No EUVD known-exploited evidence
A flaw was found in libarchive. A NULL pointer dereference vulnerability exists in the ACL parsing logic, specifically within the archive_acl_from_text_nl() function. When processing a malformed ACL string (such as a bare "d" or "default" tag without subsequent fields), the function fails to perform adequate validation before advancing the pointer. An attacker can exploit this by providing a maliciously crafted archive, causing an application utilizing the libarchive API (such as bsdtar) to crash, resulting in a Denial of Service (DoS).
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
5.5 · 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. A NULL pointer dereference vulnerability exists in the ACL parsing logic, specifically within the archive_acl_from_text_nl() function. When processing a malformed ACL string (such as a bare "d" or "default" tag without subsequent fields), the function fails to perform adequate validation before advancing the pointer. An attacker can exploit this by providing a maliciously crafted archive, causing an application utilizing the libarchive API (such as bsdtar) to crash, resulting in a Denial of Service (DoS).
What
A flaw was found in libarchive. A NULL pointer dereference vulnerability exists in the ACL parsing logic, specifically within the archive_acl_from_text_nl() function. When processing a malformed ACL string (such as a bare "d" or "default" tag without subsequent fields), the function fails to perform adequate validation before advancing the pointer. An attacker can exploit this by providing a maliciously crafted archive, causing an application utilizing the libarchive API (such as bsdtar) to crash, resulting in a Denial of Service (DoS).
Why
The product dereferences a pointer that it expects to be valid but is NULL.
How
An attacker operating through local access 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. A NULL pointer dereference vulnerability exists in the ACL parsing logic, specifically within the archive_acl_from_text_nl() function. When processing a malformed ACL string (such as a bare "d" or "default" tag without subsequent fields), the function fails to perform adequate validation before advancing the pointer. An attacker can exploit this by providing a maliciously crafted archive, causing an application utilizing the libarchive API (such as bsdtar) to crash, resulting in a Denial of Service (DoS).
Why
The product dereferences a pointer that it expects to be valid but is NULL.
How
An attacker operating through local access 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
local access → NULL Pointer Dereference → disrupt the affected service
Attack surface
Local
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-476: NULL Pointer Dereference. The product dereferences a pointer that it expects to be valid but is NULL.
CVSS vector ?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:L/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.
AVLocalAttack vector: The attacker needs local access to the vulnerable system.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
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
UnauthenticatedDenial of serviceCWE-476
A
Official authority intelligence
Only matched European and national findings are included. Language selectors and unavailable sources are omitted.
ENISA EUVD · EUVD-2026-19705Official EUVD mapping
A flaw was found in libarchive. A NULL pointer dereference vulnerability exists in the ACL parsing logic, specifically within the archive_acl_from_text_nl() function. When processing a malformed ACL string (such as a bare "d" or "default" tag without subsequent fields), the function fails to perform adequate validation before advancing the pointer. An attacker can exploit this by providing a maliciously crafted archive, causing an application utilizing the libarchive API (such as bsdtar) to crash, resulting in a Denial of Service (DoS).
Official EUVD recordBSI · German · WID-SEC-W-2026-0986libarchive: Schwachstelle ermöglicht Denial of Service
Ein entfernter, anonymer Angreifer kann eine Schwachstelle in libarchive ausnutzen, um einen Denial of Service Angriff durchzuführen.
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
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
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. Limit untrusted access and use least privilege until authoritative guidance is available.
04
Evidence and provenance
Published 7 Apr 2026 · Last source change 1 Sept 2026, 11:44 UTC · CWE-476 · NULL Pointer Dereference
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-2026-19705
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.
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
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.
CVE-2026-5745: Libarchive: a null pointer dereference vulnerability exists in the acl parser of libarchive | BlackTree
