CVE-2019-25607 in Axessh
Summary
by MITRE • 03/22/2026
Axessh 4.2 contains a stack-based buffer overflow vulnerability in the log file name field that allows local attackers to execute arbitrary code by supplying an excessively long filename. Attackers can overflow the buffer at offset 214 bytes to overwrite the instruction pointer and execute shellcode with system privileges.
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Analysis
by VulDB Data Team • 03/22/2026
The vulnerability identified as CVE-2019-25607 represents a critical stack-based buffer overflow flaw within Axessh version 4.2 software. This issue manifests specifically within the log file name field processing functionality, where inadequate input validation permits attackers to exploit memory corruption through malformed filename inputs. The vulnerability resides in the software's failure to properly bounds-check user-supplied data before copying it into fixed-size memory buffers, creating a predictable exploitation vector that can be leveraged by local adversaries.
The technical exploitation of this vulnerability occurs at a precise memory offset of 214 bytes, where the buffer overflow enables attackers to overwrite the instruction pointer and redirect program execution flow. This precise offset indicates a well-understood memory layout where the attacker can manipulate the program's execution context to inject and execute arbitrary shellcode. The vulnerability's local attack vector means that only users with existing system access can exploit this flaw, but the privilege escalation aspect allows them to execute code with system-level privileges, potentially compromising the entire system. The stack-based nature of the overflow suggests that the vulnerable code likely uses a fixed-size buffer on the stack to store the log file name, with no bounds checking mechanism to prevent excessive data from overwriting adjacent memory locations.
The operational impact of this vulnerability extends beyond simple code execution, as it provides a pathway for attackers to establish persistent system access and potentially escalate privileges to administrative levels. The local execution requirement means that attackers must first gain access to the system through other means before exploiting this vulnerability, but once exploited, the system's integrity becomes compromised. This vulnerability directly relates to CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The exploitability characteristics align with ATT&CK technique T1059.007 for command and script interpreter execution, as the shellcode execution would likely involve spawning system commands or processes with elevated privileges.
Mitigation strategies for this vulnerability require immediate software patching and updating to the latest version of Axessh that addresses the buffer overflow issue. System administrators should implement input validation controls to prevent excessively long filenames from being processed by the application, though this approach alone may not fully address the underlying memory corruption. Additional protective measures include implementing address space layout randomization and stack canaries to make exploitation more difficult, though these defenses are not foolproof against determined attackers. The vulnerability's local nature suggests that access control measures and privilege separation should be enhanced to limit the potential impact of any successful exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify similar memory corruption issues in other applications, as buffer overflows remain a prevalent class of security vulnerabilities in software systems.