Linux Telnet Authentication Bypass
Detects an authentication bypass in telnet tracked as CVE-2026-24061. An attacker can supply a specifically crafted USER environment variable (-f root) that is passed to /usr/bin/login. Because this input isn't…
Description
Detects an authentication bypass in telnet tracked as CVE-2026-24061. An attacker can supply a specifically crafted USER environment variable (-f root) that is passed to /usr/bin/login. Because this input isn't sanitized an attacker can force the system to skip authentication and login directly as root.
Detection logic
Detection requirements
- Platform
- IaaSIdentity ProviderLinuxmacOSOffice SuiteWindows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
- Log source category
- sysmon_for_linux_eventid_1
Known benign triggers
- It is rare for the telnetd to spawn login process with these arguments.
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| www.safebreach.com/blog/safebreach-labs-root-cause-analysis-and-poc-exploit-for-cve-2026-24061/ | 3from 2 sources |
From the source
- At source
- Open at source
- Upstream identifier
- 6e0913d4-5461-487c-9dce-6d22ef2c0f03
- Tagged by the source as
- Telnetd CVE-2026-24061EndpointendpointSplunk CloudSplunk EnterpriseSplunk Enterprise Securityendpoint
Licence
- Published under
- Apache License 2.0Read the licence
- Attribution
- Required
- Obtained under
- Apache-2.0Read the origin licence
Authorship
- Written by
- Published
- Aug 26, 2026
- Version
- 1