UBUNTU-CVE-2026-124737: Buffer Overflow
A flaw was found in BusyBox. When the TFTP (Trivial File Transfer Protocol) client requests a custom small block size and receives a standard response, it falls back to the default block size without resizing the allocated memory buffer. A malicious TFTP server can exploit this issue by sending standard-sized network packets during a transfer, causing a heap buffer overflow. This flaw allows an attacker to achieve arbitrary code execution or cause a Denial of Service (DoS) by crashing the application.
Affected Software
Event History
Frequently Asked Questions
What access or position does an attacker need to exploit this issue?
The attacker needs to operate or control a malicious TFTP server that the BusyBox TFTP client connects to for a transfer. Exploitation relies on the client requesting a custom small block size and then receiving standard-sized packets.
Are systems using the default TFTP block size affected?
The described condition requires the client to request a custom small block size. The provided information does not indicate that transfers using the default block size are affected.
What is the potential impact if exploitation succeeds?
A malicious TFTP server can trigger a heap buffer overflow, potentially causing the application to crash and resulting in denial of service. The flaw may also allow arbitrary code execution.