CVE-2001-0093
Description
Local users can gain root privileges on FreeBSD 1.5 by modifying critical environmental variables affecting telnetd.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Local users can gain root privileges on FreeBSD 1.5 by modifying critical environmental variables affecting telnetd.
Vulnerability
A vulnerability exists in the telnetd service on FreeBSD 1.5. Local users can exploit this by modifying critical environmental variables that influence the behavior of telnetd.
Exploitation
An attacker with local access can modify specific environmental variables. The exploit code suggests that by manipulating these variables, an attacker can trigger a condition that leads to privilege escalation.
Impact
Successful exploitation allows a local user to gain root privileges on the affected system, granting them complete control over the host.
Mitigation
No specific patch or fixed version information is available in the provided references. Users are advised to disable the telnet service if not strictly necessary or to seek alternative secure remote access methods. The affected versions include FreeBSD 1.5, and potentially other BSD variants as indicated by the exploit code's testing against BSDI BSD/OS 4.1, NetBSD 1.5, and various FreeBSD versions up to 4.3 [1].
AI Insight generated on Jun 2, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
2Patches
0No patches discovered yet.
Vulnerability mechanics
Root cause
"The telnetd daemon incorrectly handles environmental variables, allowing local users to overwrite critical memory locations and gain root privileges."
Attack vector
A local user connects to the vulnerable telnetd service. The attacker then sends a specially crafted sequence of telnet protocol commands, including setting environment variables with malicious data. This process involves sending a large amount of traffic to populate the heap with shellcode and overwrite specific memory addresses, ultimately leading to code execution as root. [ref_id=1]
Affected code
The vulnerability resides in the telnetd daemon, specifically in how it processes and handles environmental variables. The exploit code targets the `xp_setenv` function, which is responsible for sending environment variable data to the telnet daemon, and the `xp` function, which sends the final payload to trigger the overflow. [ref_id=1]
What the fix does
The provided bundle does not contain a patch or specific details on how the vulnerability was fixed. However, the advisory indicates that the vulnerability is related to the handling of environmental variables within the telnetd service. A proper fix would involve sanitizing or validating environmental variables before they are processed by telnetd to prevent memory corruption or unauthorized code execution.
Preconditions
- authThe attacker must have local access to the system or be able to connect to the telnet service.
- networkThe telnet service (port 23) must be accessible.
Generated on Jun 2, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
1News mentions
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