CVE-2026-24061
Description
CVE-2026-24061 is a critical 9.8 CVSS authentication bypass in GNU Inetutils telnetd. Secure your systems against remote root access exploits.
CPE
| Product | Version Start | Version End (excl.) | Status |
|---|---|---|---|
| inetutils | 1.9.3 | 2.7 | vulnerable |
| debian_linux | 11.0 | 11.0 | vulnerable |
Related weakness (CWE)
Remediation plan
Apply official patches
Install the latest security updates from the GNU project or your specific Linux distribution maintainers. Ensure that the patches specifically addressing the telnetd environment variable handling (commits ccba9f7 and fd702c0) are integrated into your build.
Update affected systems
Identify all deployments of GNU Inetutils between versions 1.9.3 and 2.7, as well as Debian 11 systems. Upgrade these instances to a patched version or a newer release where the authentication bypass vulnerability has been remediated.
Restrict access
Disable the telnet service (TCP port 23) entirely in favor of encrypted protocols like SSH. If telnet must remain active for legacy reasons, implement strict firewall rules or Access Control Lists (ACLs) to limit access to known, trusted management IP addresses.
Monitor for exploitation
Audit system and authentication logs for telnet sessions that bypass standard login prompts. Specifically, look for log entries or network captures containing the string '-f root' or other command-line flags within the USER environment variable negotiation.
Detection Guidance
Detecting this vulnerability requires monitoring Telnet protocol negotiation for the 'NEW-ENVIRON' option (RFC 1572). Look for network signatures where the USER variable is set to values starting with '-f'. Additionally, monitor system logs for successful root logins via telnetd that do not have corresponding successful password authentication events, which may indicate a successful bypass.