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Full vulnerability report · 2026
CVE-2026-6843High confidence

Nano: nano: format string vulnerability leads to denial of service

Red Hat · Red Hat Enterprise Linux 10

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.

Mitigation 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 releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · standard archivenanoVendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.7.2-2ubuntu0.2Canonical record ↗Source updated 11 Sept 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-2026-6843 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitynano: nano: Format string vulnerability leads to Denial of Service
9 known affected

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

  • nano.src as a component of Red Hat Enterprise Linux 10
  • nano.src as a component of Red Hat Enterprise Linux 6
  • nano.src as a component of Red Hat Enterprise Linux 7
  • nano as a component of Red Hat Enterprise Linux 8
  • nano.src as a component of Red Hat Enterprise Linux 8
  • nano as a component of Red Hat Enterprise Linux 9
  • nano.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
Summary
A flaw was found in nano. A local user could exploit a format string vulnerability in the `statusline()` function. By creating a directory with a name containing `printf` specifiers, the application attempts to display this name, leading to a segmentation fault (SEGV). This results in a Denial of Service (DoS) for the `nano` application.
Remediation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
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-2026-24708

No EUVD known-exploited evidence

A flaw was found in nano. A local user could exploit a format string vulnerability in the `statusline()` function. By creating a directory with a name containing `printf` specifiers, the application attempts to display this name, leading to a segmentation fault (SEGV). This results in a Denial of Service (DoS) for the `nano` application.

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.

Mitigation available
01

What, why and how

A flaw was found in nano. A local user could exploit a format string vulnerability in the `statusline()` function. By creating a directory with a name containing `printf` specifiers, the application attempts to display this name, leading to a segmentation fault (SEGV). This results in a Denial of Service (DoS) for the `nano` application.

What

A flaw was found in nano. A local user could exploit a format string vulnerability in the `statusline()` function. By creating a directory with a name containing `printf` specifiers, the application attempts to display this name, leading to a segmentation fault (SEGV). This results in a Denial of Service (DoS) for the `nano` application.

Why

The product uses a function that accepts a format string as an argument, but the format string originates from an external source.

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 nano. A local user could exploit a format string vulnerability in the `statusline()` function. By creating a directory with a name containing `printf` specifiers, the application attempts to display this name, leading to a segmentation fault (SEGV). This results in a Denial of Service (DoS) for the `nano` application.

Why

The product uses a function that accepts a format string as an argument, but the format string originates from an external source.

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 → Use of Externally-Controlled Format String → 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-134 ↗

CWE-134: Use of Externally-Controlled Format String. The product uses a function that accepts a format string as an argument, but the format string originates from an external source.

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-134
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-24708Official EUVD mapping

A flaw was found in nano. A local user could exploit a format string vulnerability in the `statusline()` function. By creating a directory with a name containing `printf` specifiers, the application attempts to display this name, leading to a segmentation fault (SEGV). This results in a Denial of Service (DoS) for the `nano` application.

Official EUVD record ↗
CERT-FR · French · CERTFR-2026-AVI-0558Multiples vulnérabilités dans Microsoft Azure Linux

des systèmes d'information Paris, le 11 mai 2026 N° CERTFR-2026-AVI-0558 Affaire suivie par: CERT-FR Avis du CERT-FR Objet: Multiples vulnérabilités dans Microsoft Azure Linux Gestion du document Référence CERTFR-2026-AVI-0558 Titre Multiples vulnérabilités dans Microsoft Azure Linux Date de la première version 11 mai 2026 Date de la dernière version 11 mai 2026 Source(s) Bulletin de sécurité Microsoft CVE-2026-3219 du 23 avril 2026 Bulletin de sécurité Microsoft CVE-2026-41526 du 01 mai 2026 Bulletin de sécurité Microsoft CVE-2026-4948 du 02 mai 2026 Bulletin de sécurité Microsoft CVE-2026-6842 du 03 mai 2026 Bulletin de sécurité Microsoft CVE-2026-6843 du 03 mai 2026 Bulletin de sécurité Microsoft CVE-2026-37457 du 05 mai 2026 Bulletin de sécurité Microsoft CVE-2025-71290 du 07 mai 2026 Bulletin de sécurité Microsoft CVE-2025-71293 du 07 mai 2026 Bulletin de sécurité Microsoft CVE-2025-71294 du 07 mai 2026 Bulletin de sécurité Microsoft CVE-2026-43165 du 07 mai 2026 Bulletin de sécurité Microsoft CVE-2026-43176 du 07 mai 2026 Bulletin de sécurité Microsoft CVE-2026-43191 du 07 mai 2026 Bulletin de sécurité Microsoft CVE-2026-43195 du 07 mai 2026 Bulletin de sécurité Microsoft CVE-2026-43201 du 07 mai 2026 Bulletin de sécurité Microsoft CVE-2026-43228 du 07 mai 2026 Bulletin de sécurité Mic

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.
Mitigation available
Affected
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
Workaround
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
04

Evidence and provenance

Published 22 Apr 2026 · Last source change 1 Sept 2026, 11:45 UTC · CWE-134 · Use of Externally-Controlled Format String

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-2026-24708
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD enriched

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
    nano.src as a component of Red Hat Enterprise Linux 10; nano.src as a component of Red Hat Enterprise Linux 6; nano.src as a component of Red Hat Enterprise Linux 7; nano as a component of Red Hat Enterprise Linux 8; nano.src as a component of Red Hat Enterprise Linux 8; nano as a component of Red Hat Enterprise Linux 9; nano.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
    After
    nano.src as a component of Red Hat Enterprise Linux 10; nano.src as a component of Red Hat Enterprise Linux 6; nano.src as a component of Red Hat Enterprise Linux 7; nano as a component of Red Hat Enterprise Linux 8; nano.src as a component of Red Hat Enterprise Linux 8; nano as a component of Red Hat Enterprise Linux 9; nano.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
    Red Hat Product Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2026-24708↗CVE authority or vendor reference↗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-2026-6843 · cve.blacktree.nl