Used in attacks· fix by 2026-02-169.8Critical

GNU InetUtils

CVE-2026-24061

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 this means for your business

  • It affects GNU InetUtils. It matters if your company, or a supplier that handles your data, runs it.
  • Attackers are already using it. CISA added it to its list of flaws used in real attacks on 26 January 2026.
  • An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.
  • FIRST's prediction model gives it a 99% chance of attack attempts being seen in the next 30 days, ranking above 99% of all known flaws.

What to do

  1. 1Check whether your company or your suppliers run GNU InetUtils, and which version. The affected versions are listed further down this page.
  2. 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.
  3. 3Treat it as urgent. US federal agencies must fix it by 16 February 2026. That deadline does not apply to private companies, but it shows how seriously CISA takes it.
  4. 4Because attackers have used it, check the affected systems for signs of a break-in, not only for the update.

Fastnexa security experts

Attackers are already using this flaw. Is your GNU InetUtils exposed?

Tell us where you run GNU InetUtils and a Fastnexa penetration tester will check whether this flaw, or others like it, can be used against your websites, apps and network.

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Required action

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

CISA’s wording, unedited.

Scoring

CVSS
9.8 (v3.1)
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-88
Assigned by
cve@mitre.org

Dates

Published
2026-01-26
Last modified
2026-09-30
Added to KEV
2026-01-26
Remediation due
2026-02-16
Sources
CISA KEV, NVD

Affected products

  • Gnu Inetutils1.9.3 - 2.7
  • Debian Debian Linux11.0

As listed in the NVD configuration data. Not a statement about your estate.

References