CVE-2025-15382: wolfSSH Heap Buffer Overflow Vulnerability

CVE-2025-15382 Overview

A heap buffer over-read vulnerability has been identified in the wolfSSH_CleanPath() function within wolfSSH. This vulnerability allows an authenticated remote attacker to trigger a heap over-read by one byte through specially crafted SCP path input containing '/./' sequences. The issue is classified as an Out-of-Bounds Read (CWE-125), which can potentially lead to information disclosure or denial of service conditions.

Critical Impact

Authenticated attackers can exploit crafted SCP path inputs to cause a one-byte heap over-read, potentially exposing sensitive memory contents or causing application instability.

Affected Products

• wolfSSH (versions prior to the security patch)
• Applications and systems utilizing wolfSSH for SCP functionality
• Embedded devices implementing wolfSSH for secure shell communications

Discovery Timeline

• 2026-01-06 - CVE CVE-2025-15382 published to NVD
• 2026-01-08 - Last updated in NVD database

Technical Details for CVE-2025-15382

Vulnerability Analysis

The vulnerability resides in the wolfSSH_CleanPath() function, which is responsible for sanitizing and normalizing file paths during SCP (Secure Copy Protocol) operations. When processing path strings containing specific directory traversal sequences such as '/./', the function fails to properly validate buffer boundaries, resulting in a one-byte heap over-read condition.

This type of memory safety issue can have several implications for affected systems. While the over-read is limited to one byte, it represents a memory safety boundary violation that could potentially expose adjacent heap memory contents. In certain scenarios, this could leak sensitive information or cause the application to behave unpredictably.

The attack requires the attacker to be authenticated to the wolfSSH server, which limits the exploitability to scenarios where the attacker already has valid credentials or has compromised authentication through other means.

Root Cause

The root cause of this vulnerability is insufficient bounds checking in the wolfSSH_CleanPath() function when processing directory path components. The function iterates through path segments to normalize relative path references (such as '/./' which represents the current directory), but the logic fails to account for the exact buffer boundaries when handling these sequences at certain positions within the path string.

Specifically, when the function encounters a '/./' sequence near the end of a buffer or in certain edge cases during path normalization, it reads one byte beyond the allocated heap buffer. This occurs because the pointer arithmetic or length calculations do not properly account for the null terminator or the exact allocation size of the path buffer.

Attack Vector

The attack can be executed remotely over the network by an authenticated user. The attacker must establish an SSH connection to a vulnerable wolfSSH server and initiate an SCP operation with a maliciously crafted path containing '/./' sequences designed to trigger the boundary condition error.

The exploitation flow involves:

1. The attacker authenticates to a wolfSSH server using valid credentials
2. The attacker initiates an SCP request with a crafted path containing '/./' sequences
3. The wolfSSH_CleanPath() function processes the malicious path
4. The function reads one byte beyond the allocated buffer during path normalization
5. Depending on memory layout, this could expose memory contents or cause instability

Since no verified code examples are available for this vulnerability, security researchers should refer to the GitHub Pull Request for wolfSSH for detailed technical analysis of the vulnerable code path and the implemented fix.

Detection Methods for CVE-2025-15382

Indicators of Compromise

• Unusual or malformed SCP path requests containing multiple '/./' sequences in SSH/SCP logs
• Application crashes or memory access violations in wolfSSH-based services
• Unexpected memory access patterns detected by memory sanitizers (ASan, Valgrind)

Detection Strategies

• Monitor SCP request logs for path inputs with abnormal patterns such as repeated '/./' sequences
• Deploy memory sanitization tools in development and staging environments to detect out-of-bounds access
• Implement application-level logging for the wolfSSH_CleanPath() function to capture suspicious path normalization attempts
• Use network intrusion detection systems to flag SCP sessions with unusual path patterns

Monitoring Recommendations

• Enable verbose logging on wolfSSH-enabled services to capture detailed path information during SCP operations
• Implement real-time alerting for application crashes or segmentation faults in SSH/SCP services
• Monitor system memory utilization for anomalies that could indicate exploitation attempts
• Review authentication logs for unusual patterns that may precede exploitation attempts

How to Mitigate CVE-2025-15382

Immediate Actions Required

• Apply the security patch from the wolfSSH project as soon as it becomes available
• Review and restrict SCP access to only trusted, authenticated users
• Implement network segmentation to limit exposure of wolfSSH services
• Consider temporarily disabling SCP functionality if not business-critical until patching is complete

Patch Information

The wolfSSH development team has addressed this vulnerability through a code fix. The patch is available via the GitHub Pull Request for wolfSSH. Organizations using wolfSSH should update to the patched version that includes the fix for the wolfSSH_CleanPath() function.

The fix ensures proper bounds checking during path normalization operations, preventing the one-byte heap over-read condition when processing '/./' sequences in SCP paths.

Workarounds

• Restrict access to SCP functionality through firewall rules or access control lists to limit exposure
• Implement application-level input validation to filter or reject paths containing suspicious patterns before they reach wolfSSH
• Use a web application firewall or similar technology to inspect and filter SCP requests at the network level
• Monitor for and immediately investigate any unusual SCP activity from authenticated users

# Example: Restrict SCP access via firewall (iptables)
# Limit SSH/SCP access to trusted IP ranges only
iptables -A INPUT -p tcp --dport 22 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j DROP