CVE-2026-45761 in Suricata
Summary
by MITRE • 09/10/2026
Suricata is a network Intrusion Detection System, Intrusion Prevention System and Network Security Monitoring engine. Prior to versions 7.0.16 and 8.0.5, a crafted rule using mixed-case frame syntax could trigger a heap buffer overflow while Suricata is loading signatures. The issue is reached during rule parsing/loading rather than by network traffic alone. Versions 7.0.16 and 8.0.5 contain a fix. As a workaround, preprocess rules to check that frames are all lowercase and/or only load trusted rulesets.
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Analysis
by VulDB Data Team • 09/10/2026
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 role involves the deep packet inspection of network traffic to identify malicious activity based on predefined signature rulesets. The integrity of this process relies heavily on the robust parsing of these rule definitions before they are applied to live traffic streams. A significant vulnerability was identified in versions prior to 7.0.16 and 8.0.5, where a specific flaw existed within the rule loading mechanism rather than during active packet inspection. This distinction is crucial because it changes the attack vector from requiring malicious network payloads to necessitating access to the configuration files or rulesets that Suricata loads at startup or upon reload commands.
The technical root cause of this vulnerability lies in how Suricata handles mixed-case frame syntax within crafted rule definitions. During the parsing phase, when the engine processes these specific rule structures, it fails to properly validate buffer boundaries associated with case-insensitive matching logic for certain protocol frames. This oversight leads to a heap buffer overflow condition. A heap buffer overflow occurs when data is written beyond the allocated memory space on the heap, potentially overwriting adjacent memory structures such as function pointers or metadata used by the allocator. In this context, an attacker who can influence the ruleset loaded by Suricata could craft a rule with specific mixed-case frame syntax that triggers this out-of-bounds write operation during initialization.
The operational impact of this vulnerability is severe due to its potential for remote code execution and denial of service. Since the flaw occurs during signature loading, it does not require sending malicious packets across the network to exploit; instead, exploitation requires the ability to modify or supply a ruleset file that Suricata will parse. If successfully exploited, an attacker could achieve arbitrary code execution with the privileges under which the Suricata process is running. This typically means full control over the host system hosting the IDS/IPS engine. Furthermore, even if remote code execution is not achieved, the memory corruption can cause the application to crash immediately upon loading the malformed ruleset, resulting in a denial of service that disrupts network visibility and security monitoring capabilities until the process is restarted with valid configuration files.
This vulnerability aligns with Common Weakness Enumeration (CWE) identifiers such as CWE-122: Heap-based Buffer Overflow, which describes writing data beyond the bounds of a heap allocated buffer. It also relates to CWE-787: Out-of-bounds Write in certain contexts where memory corruption leads to control flow hijacking. From an ATT&CK perspective, this flaw facilitates initial access or privilege escalation if combined with other vulnerabilities that allow rule file modification, falling under techniques related to command and script interpreter abuse or exploitation for defense evasion by disrupting security monitoring tools. The lack of strict input validation on the case sensitivity of frame syntax during the parsing phase represents a failure in secure coding practices regarding memory management and boundary checks.
To mitigate this risk, organizations running affected versions must upgrade immediately to Suricata version 7.0.16 or later, where the developers have implemented fixes for the buffer overflow condition. For environments that cannot be upgraded instantly, a recommended workaround involves preprocessing all rulesets before loading them into Suricata. This process should include automated checks to ensure that frame syntax is strictly lowercase, thereby neutralizing the specific trigger condition required to exploit the flaw. Additionally, administrators must enforce strict access controls on configuration directories and implement integrity monitoring solutions such as file integrity checkers to detect any unauthorized modifications to ruleset files. By ensuring only trusted and validated rule sets are loaded, organizations can significantly reduce the attack surface associated with this vulnerability until a permanent patch is applied.