UBUNTU-CVE-2026-94184: Buffer Overflow
A stack-based buffer overflow flaw was found in fetchmail when built with NTLM support. A malicious or compromised mail server advertising NTLM authentication can send a crafted Type 2 challenge that causes fetchmail to write past a fixed stack buffer while building the NTLM authenticate response. This may lead to remote code execution depending on stack-frame layout, or to authentication failure or process termination under memory hardening.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed?
Fetchmail deployments built with NTLM support are exposed when they connect to a mail server that advertises NTLM authentication. The server may be malicious or compromised.
What does an attacker need to exploit this issue?
An attacker needs to control, or compromise, a mail server that the affected fetchmail instance connects to and have it send a crafted NTLM Type 2 challenge. No prior authentication or user interaction is indicated by the supplied severity vector.
What are the likely outcomes of exploitation?
The overflow may permit remote code execution depending on the stack-frame layout. Where memory hardening prevents code execution, it can still cause authentication failure or terminate the fetchmail process.