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Full vulnerability report · 2026
CVE-2026-6862High confidence

Efivar: efivar: denial of service due to stack overflow in device path node parsing

Red Hat · Red Hat Hardened Images

Official source article: Red Hat RHSA-2026:69321 ↗. Check the applicable product and release in the original source.

5.5MediumCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 18 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
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 0.17% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict local access and enforce least privilege on affected hosts.
  • 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.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 18 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

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
Package result overrides the generic status

BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 4 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.

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 · sourceefivarAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourceefivarAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourceefivarAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourceefivarAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 5 Oct 2026
Ubuntu 24.04 LTSnoble · standard archiveefivarUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical 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-2026-6862 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityefivar: efivar: Denial of Service due to stack overflow in device path node parsing
14 under investigation

The vendor has not yet reached a final affected or unaffected determination for these products.

  • efivar-devel as a component of Red Hat Enterprise Linux 10
  • efivar-libs as a component of Red Hat Enterprise Linux 10
  • efivar.src as a component of Red Hat Enterprise Linux 10
  • efivar-devel as a component of Red Hat Enterprise Linux 7
  • efivar-libs as a component of Red Hat Enterprise Linux 7
  • efivar.src as a component of Red Hat Enterprise Linux 7
  • efivar-devel as a component of Red Hat Enterprise Linux 8
  • efivar-libs as a component of Red Hat Enterprise Linux 8
  • efivar.src as a component of Red Hat Enterprise Linux 8
  • efivar-devel as a component of Red Hat Enterprise Linux 9
  • efivar-libs as a component of Red Hat Enterprise Linux 9
  • efivar.src as a component of Red Hat Enterprise Linux 9
Summary
A flaw was found in libefiboot, a component of efivar. The device path node parser in libefiboot fails to validate that each node's Length field is at least 4 bytes, which is the minimum size for an EFI (Extensible Firmware Interface) device path node header. A local user could exploit this vulnerability by providing a specially crafted device path node. This can lead to infinite recursion, causing stack exhaustion and a process 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.

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-2026-24957

No EUVD known-exploited evidence

A flaw was found in libefiboot, a component of efivar. The device path node parser in libefiboot fails to validate that each node's Length field is at least 4 bytes, which is the minimum size for an EFI (Extensible Firmware Interface) device path node header. A local user could exploit this vulnerability by providing a specially crafted device path node. This can lead to infinite recursion, causing stack exhaustion and a process 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 actionPatch only the product branches with a verified fix

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority. Verified remediation exists for at least one product or source, but 18 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

A flaw was found in libefiboot, a component of efivar. The device path node parser in libefiboot fails to validate that each node's Length field is at least 4 bytes, which is the minimum size for an EFI (Extensible Firmware Interface) device path node header. A local user could exploit this vulnerability by providing a specially crafted device path node. This can lead to infinite recursion, causing stack exhaustion and a process crash, resulting in a denial of service (DoS).

What

A flaw was found in libefiboot, a component of efivar. The device path node parser in libefiboot fails to validate that each node's Length field is at least 4 bytes, which is the minimum size for an EFI (Extensible Firmware Interface) device path node header. A local user could exploit this vulnerability by providing a specially crafted device path node. This can lead to infinite recursion, causing stack exhaustion and a process crash, resulting in a denial of service (DoS).

Why

The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

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 libefiboot, a component of efivar. The device path node parser in libefiboot fails to validate that each node's Length field is at least 4 bytes, which is the minimum size for an EFI (Extensible Firmware Interface) device path node header. A local user could exploit this vulnerability by providing a specially crafted device path node. This can lead to infinite recursion, causing stack exhaustion and a process crash, resulting in a denial of service (DoS).

Why

The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

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 → Uncontrolled Recursion → 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-674 ↗

CWE-674: Uncontrolled Recursion. The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

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-674
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-24957Official EUVD mapping

A flaw was found in libefiboot, a component of efivar. The device path node parser in libefiboot fails to validate that each node's Length field is at least 4 bytes, which is the minimum size for an EFI (Extensible Firmware Interface) device path node header. A local user could exploit this vulnerability by providing a specially crafted device path node. This can lead to infinite recursion, causing stack exhaustion and a process crash, resulting in a denial of service (DoS).

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260429Security Bulletin 29 Apr 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 29 Apr 2026, published on 29 April 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-015519ubuntuのlibefibootにおける再帰制御に関する脆弱性

libefiboot（efivarのコンポーネント）に脆弱性が発見されました。libefibootのデバイスパスノードパーサは、各ノードのLengthフィールドが最小サイズである4バイト以上であることを検証していません。この脆弱性は、ローカルユーザーが特別に細工されたデバイスパスノードを提供することで悪用可能です。これにより無限再帰が発生し、スタック枯渇やプロセスクラッシュを引き起こし、サービス拒否（DoS）状態をもたらす可能性があります。

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.
Fix availability varies by product
Affected
Red Hat Hardened Images: patch: 39-13.1.hum1
Fixed
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 22 Apr 2026 · Last source change 21 Sept 2026, 17:27 UTC · CWE-674 · Uncontrolled Recursion

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-2026-24957
Product sourceCNA
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD modified after enrichment

Missing structured fields: affected versions. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: removed vendor advisory: access.redhat.com/RHSA-2026:69321.
    Before
    remediation: access.redhat.com/RHSA-2026:69321 · vendor advisory: access.redhat.com/RHSA-2026:69321
    After
    remediation: access.redhat.com/RHSA-2026:69321
    CNA ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added remediation: access.redhat.com/RHSA-2026:69321; added vendor advisory: access.redhat.com/RHSA-2026:69321.
    Before
    no authoritative guidance recorded
    After
    remediation: access.redhat.com/RHSA-2026:69321 · vendor advisory: access.redhat.com/RHSA-2026:69321
    access.redhat.com ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    See the vendor and CVE records for the affected range. · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    See the vendor and CVE records for the affected range. · Fixed: Red Hat Hardened Images: 39-13.1.hum1 < *
    CNA ↗
  4. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    access.redhat.com ↗
  5. Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-6862 to remediation: access.redhat.com/CVE-2026-6862.
    Before
    remediation: access.redhat.com/CVE-2026-6862
    After
    remediation: access.redhat.com/CVE-2026-6862
    Red Hat Product Security ↗
  6. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    Red Hat Product Security ↗
  7. Affected versionsThe structured affected or fixed version information changed.
    Before
    After
    Fixed: efivar-0:39-13.1.hum1@aarch64 as a component of Red Hat Hardened Images; efivar-0:39-13.1.hum1@src as a component of Red Hat Hardened Images; efivar-0:39-13.1.hum1@x86_64 as a component of Red Hat Hardened Images; efivar-devel-0:39-13.1.hum1@aarch64 as a component of Red Hat Hardened Images; efivar-devel-0:39-13.1.hum1@x86_64 as a component of Red Hat Hardened Images; efivar-libs-0:39-13.1.hum1@aarch64 as a component of Red Hat Hardened Images; efivar-libs-0:39-13.1.hum1@x86_64 as a component of Red Hat Hardened Images
    Red Hat Product Security ↗
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-2026-24957↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference · Red Hat RHSA-2026:69321↗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-2026-6862 · cve.blacktree.nl