CVE-2026-63449 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, the SIP parser in rust/src/sip/parser.rs stores request and response body lengths in 16-bit fields. A SIP body larger than 65,536 bytes can truncate the length and prevent frame:request.body or frame:response.body from exposing the complete body to inspection, allowing content in the omitted portion to evade frame-based detection. This issue is fixed in version 8.0.6.
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Analysis
by VulDB Data Team • 09/19/2026
The vulnerability identified within Suricata versions ranging from 8.0.0 through 8.0.6 stems from a fundamental data type limitation in its Session Initiation Protocol parser implementation located at rust/src/sip/parser.rs. Specifically, the system utilizes sixteen-bit unsigned integer fields to store the lengths of SIP request and response bodies. This architectural choice imposes a hard ceiling on the maximum body size that can be accurately represented, which is calculated as two raised to the power of sixteen minus one, resulting in a limit of 65,535 bytes or potentially 65,536 bytes depending on zero-based indexing conventions. When an incoming SIP message contains a payload exceeding this threshold, the integer value representing the body length undergoes arithmetic overflow, causing it to wrap around and store only the lower sixteen bits of the actual size. This truncation effectively masks the true magnitude of the data being transmitted within the network stream.
From a technical perspective, this flaw directly impacts the integrity of frame-based inspection mechanisms employed by Suricata for deep packet analysis. The parser relies on these length fields to delineate where the SIP header ends and the body begins, as well as how much subsequent data belongs to that specific message structure. Due to the truncated length value, the engine incorrectly calculates the boundaries of the payload, leading it to ignore or discard the portion of the body that exceeds the 65,536-byte limit. Consequently, any malicious content embedded within this omitted segment is never passed to the detection engines responsible for analyzing frame:body and response:body fields. This creates a blind spot in the security monitoring infrastructure where attackers can hide exploits, command-and-control communications, or data exfiltration payloads that remain invisible to standard signature-based and heuristic analysis tools operating on SIP traffic.
The operational impact of this vulnerability is significant for organizations relying on Suricata for network intrusion detection and prevention services. By allowing content within large SIP bodies to evade inspection, the flaw undermines the core security posture provided by the system. Attackers can exploit this limitation to conduct sophisticated attacks that do not trigger alerts because they reside in the unanalyzed portion of the packet stream. This is particularly dangerous given that SIP is a critical protocol for Voice over IP communications and often carries sensitive media streams or signaling data. The ability to bypass detection mechanisms means that potential threats such as buffer overflow attempts, injection attacks, or malicious script execution within SIP payloads can proceed undetected, potentially leading to unauthorized access, service disruption, or compromise of underlying systems connected via the VoIP infrastructure.
This issue is classified under Common Weakness Enumeration standards as CWE-190 Integer Overflow or Wraparound and aligns with ATT&CK techniques related to evasion such as T1564 Hidden Files and Directories in the context of hiding malicious payloads within protocol structures, although more specifically it represents a parsing logic failure that facilitates evasion. To mitigate this risk, organizations must ensure their Suricata deployments are updated to version 8.0.6 or later where the parser has been corrected to handle larger body sizes appropriately, likely by utilizing wider data types such as thirty-two-bit integers for length fields. Additionally, administrators should implement network segmentation and additional monitoring layers that can provide redundancy in case of future parsing vulnerabilities. Regular updates to intrusion detection system signatures and engine software are essential to maintain visibility into evolving attack vectors targeting protocol parsers.