CVE-2026-45763 in Suricata
Summary
by MITRE • 09/10/2026
Suricata is a network Intrusion Detection System, Intrusion Prevention System and Network Security Monitoring engine. Starting in version 8.0.0 and prior to version 8.0.5,when Lua rule execution is enabled, the Lua sandbox memory limit was not consistently enforced for new allocations. Certain Lua allocation patterns could exceed `security.lua.max-bytes` without triggering the intended memory limit, making the configured sandbox limit unreliable. This requires Lua rules to be enabled and an affected Lua script/rule to be loaded. Version 8.0.5 contains a fix. As a workaround, disable `security.lua.allow-rules` unless Lua rules are required.
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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 capability to execute custom logic through embedded scripting languages like Lua allows for highly specialized threat detection that goes beyond static signature matching. However, the integration of such dynamic execution environments introduces complex memory management challenges. In versions starting from 8.0.0 up to but not including 8.0.5, a significant flaw was identified within the Lua sandbox implementation regarding how memory limits are enforced during rule execution. This vulnerability stems from an inconsistency in the enforcement mechanisms for new memory allocations made by Lua scripts running under the security context of Suricata.
The core technical flaw involves the failure to consistently enforce the `security.lua.max-bytes` configuration parameter when handling specific allocation patterns within the Lua environment. While the intention was to restrict the amount of memory a single Lua rule or script could consume, preventing resource exhaustion attacks, certain allocation strategies allowed scripts to bypass this limit entirely. By exploiting these specific patterns, an attacker or malicious actor could cause the Lua sandbox to allocate memory beyond the configured threshold without triggering the intended protective mechanisms. This inconsistency renders the security boundary unreliable, as the system fails to cap memory usage effectively during critical inspection phases where rules are actively processing network traffic.
The operational impact of this vulnerability is primarily centered on resource exhaustion and potential denial of service conditions for the Suricata instance itself. Since Lua scripts often run in a context that processes live network packets or stored logs, an uncontrolled memory allocation can lead to rapid consumption of system RAM. This can cause the Suricata process to become unstable, crash, or be terminated by the operating system's out-of-memory killer, resulting in a loss of visibility and protection for the monitored network segment. Furthermore, if the Lua script is designed with malicious intent, this flaw could potentially facilitate more sophisticated attacks against the host system running Suricata, although the primary risk remains the degradation of security monitoring capabilities due to resource depletion.
From a classification perspective, this issue aligns with CWE-789: Memory Allocation with Excessive Size or Count, as it involves improper handling of memory allocation limits leading to potential denial of service. It also relates to CWE-20: Improper Input Validation in the context of how the sandbox validates and restricts resource usage based on configuration parameters. In terms of attack vectors, this vulnerability could be leveraged within the ATT&CK framework under techniques related to Resource Hijacking or Denial of Service, specifically where an adversary exploits software vulnerabilities to disrupt service availability rather than gaining unauthorized access to data.
To mitigate this risk, organizations running Suricata versions between 8.0.0 and 8.0.4 should immediately upgrade to version 8.0.5 or later, which contains the necessary code corrections to ensure consistent enforcement of memory limits within the Lua sandbox. For environments where upgrading is not immediately feasible, a recommended workaround is to disable the execution of Lua rules by setting `security.lua.allow-rules` to false in the configuration file. This action effectively neutralizes the attack vector by preventing any Lua scripts from executing, thereby eliminating the possibility of exploiting the memory limit bypass. It is crucial to assess whether custom Lua-based detection logic is actively required for specific threat hunting or prevention scenarios before disabling this feature, as doing so will remove those capabilities until a proper upgrade can be performed.