CVE-2026-53994
Description
A flaw was found in ProFTPD's mod_sftp module. An authenticated SFTP user can exploit a heap-based buffer overflow by sending a specially crafted SFTP packet with a zero-length value. This can lead to an unsigned integer underflow, causing the system to allocate a small memory block while expecting a much larger one. Consequently, an attacker can write beyond the allocated buffer, resulting in a reliable remote Denial of Service (DoS) by crashing the ProFTPD session. Depending on memory layout, further impacts such as arbitrary code execution may be possible.
Statement
Red Hat Product Security has determined that this vulnerability does not affect any currently supported Red Hat product. This assessment may evolve based on further analysis and discovery. For more information about this vulnerability and the products it affects, please see the linked references.
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Instability
This weakness will generally lead to undefined behavior and therefore crashes. In the case of overflows involving loop index variables, the likelihood of infinite loops is also high.
Integrity
Technical Impact: Modify Memory
If the value in question is important to data (as opposed to flow), simple data corruption has occurred. Also, if the wrap around results in other conditions such as buffer overflows, further memory corruption may occur.
Confidentiality,Availability,Access Control
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism
This weakness can sometimes trigger buffer overflows which can be used to execute arbitrary code. This is usually outside the scope of a program's implicit security policy.
Frequently Asked Questions
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