CVE-2026-3606: Ettercap Buffer Overflow Vulnerability

CVE-2026-3606 Overview

A memory safety vulnerability has been identified in Ettercap 0.8.4-Garofalo, a comprehensive suite for man-in-the-middle attacks on local area networks. The vulnerability exists in the add_data_segment function within the src/ettercap/utils/etterfilter/ef_output.c file of the etterfilter component. When processing maliciously crafted input, the function performs an out-of-bounds read operation, potentially exposing sensitive memory contents or causing application instability.

Critical Impact

Local attackers with low privileges can exploit this out-of-bounds read vulnerability in the etterfilter utility to cause denial of service or potentially leak sensitive memory information.

Affected Products

• Ettercap 0.8.4-Garofalo
• etterfilter component (src/ettercap/utils/etterfilter/ef_output.c)

Discovery Timeline

• 2026-03-05 - CVE-2026-3606 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-3606

Vulnerability Analysis

This vulnerability is classified as an out-of-bounds read (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the add_data_segment function of the etterfilter utility, which is used to compile filter scripts for use with Ettercap's content filtering capabilities.

When the vulnerable function processes specially crafted input data, it fails to properly validate buffer boundaries before performing read operations. This allows an attacker to trigger memory access beyond the allocated buffer boundaries. While the attack requires local access and low-level privileges, the exploit has been publicly disclosed, increasing the risk of active exploitation.

The vulnerability primarily impacts system availability, as out-of-bounds reads can cause application crashes or undefined behavior. Additionally, there is potential for information disclosure if the out-of-bounds memory access exposes sensitive data from adjacent memory regions.

Root Cause

The root cause of this vulnerability is insufficient bounds checking in the add_data_segment function when handling data segment operations. The function does not properly validate the size and boundaries of memory operations, allowing read operations to exceed the allocated buffer limits. This is a classic memory corruption issue stemming from improper input validation and lack of defensive programming practices when handling user-controlled data.

Attack Vector

Exploitation of this vulnerability requires local access to the target system. An attacker with low-privilege access can exploit this flaw by providing specially crafted input to the etterfilter utility. The attack does not require user interaction and has low complexity. The public disclosure of exploitation techniques through the GitHub PoC Repository increases the likelihood of exploitation attempts.

The attacker would need to craft a malicious filter file or input that, when processed by etterfilter, triggers the out-of-bounds read condition in the add_data_segment function. This could lead to application crashes (denial of service) or potentially expose memory contents.

Detection Methods for CVE-2026-3606

Indicators of Compromise

• Unexpected crashes or segmentation faults in the etterfilter process
• Abnormal memory access patterns or coredumps from etterfilter utility
• Suspicious filter files being processed by the etterfilter component
• Unusual error messages related to memory operations in Ettercap logs

Detection Strategies

• Monitor for unexpected termination or crashes of the etterfilter process
• Implement file integrity monitoring on Ettercap filter files and configuration
• Deploy memory protection tools like AddressSanitizer (ASan) during testing to detect out-of-bounds reads
• Review system logs for segmentation fault signals (SIGSEGV) associated with etterfilter

Monitoring Recommendations

• Configure SentinelOne endpoint protection to alert on suspicious etterfilter process behavior
• Enable process monitoring to detect abnormal memory access patterns
• Implement audit logging for all etterfilter invocations and their input parameters
• Monitor for creation or modification of filter files in Ettercap directories

How to Mitigate CVE-2026-3606

Immediate Actions Required

• Restrict access to the etterfilter utility to only authorized security personnel
• Limit local system access to reduce the attack surface for this local exploit
• Implement application whitelisting to control etterfilter execution
• Review and validate all filter files before processing with etterfilter

Patch Information

As of the last update, the Ettercap project has been notified of this vulnerability through GitHub Issue #1297 but has not yet responded. No official patch is currently available. Organizations should monitor the Ettercap GitHub Repository for security updates and apply patches as soon as they become available. Additional vulnerability details can be found at VulDB #349218.

Workarounds

• Restrict execution permissions for the etterfilter binary to trusted administrators only
• Consider using containerization or sandboxing when running etterfilter to limit potential impact
• Implement strict input validation for any filter files before processing
• Temporarily disable or remove etterfilter if not required for operations

# Configuration example
# Restrict etterfilter permissions to root only
sudo chmod 700 /usr/bin/etterfilter
sudo chown root:root /usr/bin/etterfilter

# Alternatively, restrict to a security group
sudo groupadd ettercap-admins
sudo chown root:ettercap-admins /usr/bin/etterfilter
sudo chmod 750 /usr/bin/etterfilter