CVE-2026-63451 in Suricata
Summary
by MITRE • 09/19/2026
Suricata is a network Intrusion Detection System, Intrusion Prevention System and Network Security Monitoring engine. From 8.0.0 until 8.0.6, a locally supplied detection rule that combines frame inspection without content and a transformed match without content can make src/detect-engine-prefilter.c select multiple non-prefilter frame engines while preparing signatures for non-prefilter inspection. Loading the crafted rule, including in test mode, can trigger a heap buffer overflow and crash Suricata; network traffic alone cannot reach the flaw. This issue is fixed in version 8.0.6.
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Analysis
by VulDB Data Team • 09/19/2026
Suricata serves as a critical component in modern network security infrastructure, functioning simultaneously as an Intrusion Detection System, an Intrusion Prevention System, and a Network Security Monitoring engine. Its primary operational mechanism involves parsing incoming network traffic against a comprehensive set of detection rules to identify malicious activity or policy violations. The integrity of this process relies heavily on the efficient classification and execution of these rules through various inspection engines designed to handle different types of pattern matching and protocol analysis. Within versions 8.0.0 through 8.0.6, a specific architectural flaw exists within the signature preparation logic that affects how certain rule combinations are processed prior to actual packet inspection.
The technical vulnerability resides in the source file detect-engine-prefilter.c, which is responsible for optimizing detection rules by identifying those that can be handled efficiently without full content matching overhead. The flaw occurs when a locally supplied detection rule combines frame inspection without specific content requirements alongside a transformed match also lacking content specifications. This particular combination confuses the prefilter selection logic, causing it to incorrectly select multiple non-prefilter frame engines during the signature preparation phase for non-prefilter inspection. Instead of correctly categorizing or optimizing these rules, the engine enters an invalid state where memory allocation and management operations are performed erroneously.
This misconfiguration leads directly to a heap buffer overflow condition when the crafted rule is loaded into Suricata. The vulnerability is strictly local in nature, meaning it cannot be triggered by external network traffic alone. An attacker must have the ability to supply or modify detection rules on the host system running Suricata. This could occur through compromised configuration management systems, unauthorized access to the file system where rules are stored, or via a privileged user who can inject malicious rule sets into the engine's configuration. Once such a rule is loaded, including during test mode validations which are often used by administrators to verify rule syntax before deployment, the memory corruption occurs immediately due to the improper handling of multiple frame engines.
The operational impact of this vulnerability includes immediate service disruption through application crashes. Since Suricata typically runs as a persistent daemon responsible for continuous network monitoring, a crash results in a denial of service condition where all security visibility and protection capabilities are lost until the process is restarted. In environments relying on Intrusion Prevention System modes, this interruption could allow malicious traffic to pass undetected during the downtime window. Furthermore, while heap buffer overflows can sometimes lead to arbitrary code execution depending on memory layout and exploitability conditions, in this specific context involving Suricata's rule loading mechanism, the primary confirmed impact is stability degradation through crashes rather than remote code execution via network packets.
Mitigation strategies focus primarily on version upgrades and access control hardening. The most effective remediation is to upgrade Suricata to version 8.0.6 or later, where this logic error in detect-engine-prefilter.c has been corrected to properly handle the specified rule combinations without triggering memory corruption. For environments unable to immediately patch, strict file system permissions should be enforced on configuration directories and rule files to prevent unauthorized users from injecting malicious detection rules. Additionally, administrators should limit who can reload or modify Suricata configurations in production environments, ensuring that only trusted personnel with verified change management approvals can alter the inspection engine's behavior.
From a classification perspective, this vulnerability aligns with CWE-122, which denotes heap-based buffer overflow, as it involves writing data beyond the bounds of an allocated heap region due to flawed logic. It also relates to CWE-787, regarding out-of-bounds write access in specific contexts where memory management fails under edge cases. In terms of adversary tactics, this flaw does not map directly to a remote exploitation technique within MITRE ATT&CK because it requires local rule injection rather than network-based attack vectors. However, the potential for denial of service through application crash maps to T1499, Endpoint Denial of Service, if an attacker successfully compromises the host and triggers the condition intentionally. The vulnerability highlights the importance of rigorous input validation even in internal configuration processing paths where trust assumptions might otherwise lead to insufficient security checks.