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Full vulnerability report · 2026
CVE-2026-24061High confidence

GNU InetUtils Argument Injection Vulnerability

GNU · Inetutils

9.8CriticalCVSS 3.1
Recommended action
Patch now

CISA confirms exploitation in the wild and lists 2026-02-16 as the remediation due date.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:Critical, unchanged from published severity.unchanged

Evidence used

  • CISA confirms exploitation in the wild.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 98.98% 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.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs GNU Inetutils 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: Within 3 daysRemediation target: Within 90 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 · sourceinetutilsVendor fix publishedDebian records a fixed source-package version for this release.2:2.6-3+deb13u1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourceinetutilsVendor fix publishedDebian records a fixed source-package version for this release.2:2.4-2+deb12u2Debian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourceinetutilsVendor fix publishedDebian records a fixed source-package version for this release.2:2.7-2Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourceinetutilsVendor fix publishedDebian records a fixed source-package version for this release.2:2.7-2Debian Security Tracker ↗Source updated 6 Oct 2026
Ubuntu 24.04 LTSnoble · standard archiveinetutilsVendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.2:2.5-3ubuntu4.1Canonical Ubuntu Security ↗Source updated 5 Oct 2026
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-2026-3688

CISA KEV mirrored by ENISA

telnetd in GNU Inetutils through 2.7 allows remote authentication bypass via a "-f root" value for the USER environment variable.

EUVD state
Present in the current official mapping
Known exploitation
Recorded by ENISA since 26 Jan 2026. Evidence sources: cisa_kev.
ENISA score
9.8 · CVSS 3.1
Advisory evidence
2 linked advisory records
Explicit mitigation evidence

Only statements that explicitly mention a fix, patch, update, workaround or mitigation are shown here.

  • csaf_ncscnl · NCSC-2026-0033Kwetsbaarheid verholpen in GNU Inetutils telnetd
Recommended actionPatch now

CISA confirms exploitation in the wild and lists 2026-02-16 as the remediation due date.

Patch available
01

What, why and how

GNU InetUtils contains an argument injection vulnerability in telnetd that could allow for remote authentication bypass via a "-f root" value for the USER environment variable.

What

GNU InetUtils contains an argument injection vulnerability in telnetd that could allow for remote authentication bypass via a "-f root" value for the USER environment variable.

Why

The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may bypass an access boundary or take over an account.

What

GNU InetUtils contains an argument injection vulnerability in telnetd that could allow for remote authentication bypass via a "-f root" value for the USER environment variable.

Why

The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may bypass an access boundary or take over an account.

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.
Confirmed in the wild

CISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2026-01-26.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Improper Neutralization of Argument Delimiters in a Command ('Argument Injection') → bypass an access boundary or take over an account
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
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-88 ↗

CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection'). The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.

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:N/S:U/C:H/I:H/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.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
Stolen credentials, tokens and legitimate administration functions may provide continued access without deploying a large custom toolset.
NetworkUnauthenticatedCWE-88CISA KEVPublic exploit reference
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-3688Known-exploited evidence recorded

telnetd in GNU Inetutils through 2.7 allows remote authentication bypass via a "-f root" value for the USER environment variable.

Official EUVD record ↗
BSI · German · WID-SEC-2026-0183InetUtils (telnetd): Schwachstelle ermöglicht Erlangen von Administratorrechten

Ein entfernter, anonymer Angreifer kann eine Schwachstelle im "telnetd" der InetUtils ausnutzen, um die Authentifizierung zu umgehen und Root-Zugriff zu erlangen.

Official advisory ↗
Canadian Centre for Cyber Security · English · AL26-002AL26-002 -Vulnerability affecting GNU Inetutils Telnetd - CVE-2026-24061

An Alert is used to raise awareness of a recently identified cyber threat that may impact cyber information assets, and to provide additional detection and mitigation advice to recipients. The Canadian Centre for Cyber Security ("Cyber Centre") is also available to provide additional assistance regarding the content of this Alert to recipients as requested.

Official advisory ↗
Canadian Centre for Cyber Security · English · AV26-047GNU security advisory (AV26-047) – Update 1

On January 21, 2026, GNU published a security advisory to address a vulnerability in the following product. Included was a critical update for the following: Update 1 On January 26, 2026, Cybersecurity and Infrastructure Security Agency (CISA) added CVE-2026-24061 to their Known Exploited Vulnerabilities (KEV) Database.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260128Security Bulletin 28 Jan 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 28 Jan 2026, published on 28 January 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0143Multiples vulnérabilités dans Synology Storage Manager

De multiples vulnérabilités ont été découvertes dans Synology Storage Manager. Elles permettent à un attaquant de provoquer une atteinte à la confidentialité des données.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-001978Debian等の複数ベンダの製品における引数の挿入または変更に関する脆弱性

GNU Inetutils 2.7までのtelnetdには、USER環境変数に「-f root」という値を設定することでリモート認証を回避できる脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-6672GNU Inetutils 취약점 보안 업데이트 권고

GNU Inetutils의 telnetd(Telnet daemon)에서 발생하는 인증우회 취약점(CVE-2026-24061) [1][4]

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-6673美 CISA 발표 주요 Exploit 정보공유(Update. 2026-01-26)

GNU InetUtils contains an argument injection vulnerability in telnetd that could allow for remote authentication bypass via a "-f root" value for the USER environment variable.

Official advisory ↗
NCSC-NL · Dutch · NCSC-2026-0033Kwetsbaarheid verholpen in GNU Inetutils telnetd

The GNU Inetutils telnetd version 2.7 is susceptible to a remote authentication bypass due to the manipulation of the USER environment variable to '-f root'.

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
Inetutils: 1.9.3 ≤ 2.7
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
A mitigation or workaround reference is available from the source linked below; validate it against the affected product and version.
04

Evidence and provenance

Published 21 Jan 2026 · Last source change 29 Sept 2026, 19:43 UTC · CWE-88 · Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')

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-2026-3688
Product sourceCNA
Remediation sourceCVE/CNA references
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. Public exploit evidencePublic exploit evidence changed from Public exploit reference to Public exploit reference.
    Before
    Public exploit reference
    After
    Public exploit reference
    cve@mitre.org ↗
  2. Affected versionsThe structured affected or fixed version information changed.
    Before
    1.9.3 ≤ 2.7 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    After
    Inetutils: 1.9.3 ≤ 2.7 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Added to CISA KEV
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-3688↗CISA KEV record↗Mitigation reference↗Patch or update reference↗Patch or update reference↗Mitigation reference↗CVE authority or vendor reference↗Public exploit reference↗Public exploit reference↗
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-2026-24061 · cve.blacktree.nl