GNU InetUtils Argument Injection
CVE-2026-24061 is a critical-severity improper neutralization of argument delimiters in a command vulnerability in Inetutils from GNU, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Inetutils versions: 1.9.3 through 2.7. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on January 26, 2026, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Check which version of Inetutils you run against the affected versions below, and install the vendor's latest release.
- CISA's 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.
- Read the advisory on lists.gnu.org for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| GNU | Inetutils | 1.9.3 through 2.7 | Not stated |
| Debian | Debian Linux | 11.0 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (mitre.org).
Official description
telnetd in GNU Inetutils through 2.7 allows remote authentication bypass via a "-f root" value for the USER environment variable.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Argument Delimiters in a Command
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 developers prevent this class of flaw
- Understand all the potential areas where untrusted inputs can enter your product: parameters or arguments, cookies, anything read from the network, environment variables, request headers as well as content, URL components, e-mail, files, databases, and any external systems that provide data to the application. Perform input validation at well-defined interfaces.
- Directly convert your input type into the expected data type, such as using a conversion function that translates a string into a number. After converting to the expected data type, ensure that the input's values fall within the expected range of allowable values and that multi-field consistencies are maintained.
- When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.
More Improper Neutralization of Argument Delimiters in a Command vulnerabilities (CWE-88)
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
- Deadline for US federal agencies to remediate, set by CISA.
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
- codeberg.org/inetutils/inetutils/commit/ccba9f748aa8d50a38d7748e2e60362edd6a32cc
- codeberg.org/inetutils/inetutils/commit/fd702c02497b2f398e739e3119bed0b23dd7aa7b
- vicarius.io/vsociety/posts/cve-2026-24061-mitigation-script-remote-authentication-bypass-in-gnu-inetutils-pac…Mitigation, Third Party Advisory
Third-party and government advisories
- vicarius.io/vsociety/posts/cve-2026-24061-detection-script-remote-authentication-bypass-in-gnu-inetutils-pack…Third Party Advisory
- lists.debian.org/debian-lts-announce/2026/01/msg00025.htmlMailing List, Third Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-24061US Government Resource
- openwall.com/lists/oss-security/2026/01/20/2#:~:[email protected]%3A~%20USER='Mailing List, Third Party Advisory
Technical write-ups (may include proof of concept)
- redteam.ae/blog/cve-2026-24061-inetutils-telnetd-root-bypassExploit, Third Party Advisory
- labs.greynoise.io/grimoire/2026-01-22-f-around-and-find-out-18-hours-of-unsolicited-houseguests/index.htmlExploit, Third Party Advisory
Other references
- gnu.org/software/inetutils/Product
- openwall.com/lists/oss-security/2026/01/20/2Mailing List
- openwall.com/lists/oss-security/2026/01/20/8Mailing List
- openwall.com/lists/oss-security/2026/01/22/1Mailing List
Other vulnerabilities in Inetutils
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
- 7.5 High severity
Recent Improper Neutralization of Argument Delimiters in a Command vulnerabilities
- 7.0 High severity
- 7.1 High severity
- 7.5 High severity
- 8.7 High severity
- 8.6 High severity
- 8.8 High severity
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