CVE-2026-66733 in Sonic3air
Summary
by MITRE • 08/06/2026
Sonic 3 A.I.R. before commit 2492d18 contains an unbounded memory allocation vulnerability in ReceivedPacketCache::enqueuePacket() that allows unauthenticated remote attackers to crash the server process by sending a crafted UDP packet with mUniquePacketID set to the maximum uint32 value. The mUniquePacketID field is read directly from the UDP wire-format packet header without bounds checking, causing the server to allocate one CacheItem per missing packet ID gap, exhausting available host memory and propagating an uncaught std::bad_alloc exception to std::terminate().
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Analysis
by VulDB Data Team • 08/06/2026
This vulnerability exists within the Sonic 3 A.I.R. gaming server software prior to commit 2492d18 and represents a critical memory management flaw that can be exploited remotely without authentication. The issue manifests in the ReceivedPacketCache::enqueuePacket() function where the mUniquePacketID field is directly extracted from incoming UDP packet headers without proper validation or bounds checking. When an attacker sends a crafted UDP packet with the maximum possible uint32 value (4294967295) as the packet ID, the server processes this value as if it were a legitimate sequential identifier. This design flaw creates a scenario where the system attempts to allocate memory resources proportional to the gap between consecutive packet IDs, resulting in exponential memory consumption.
The technical implementation of this vulnerability stems from inadequate input validation and memory allocation strategies within the network packet processing pipeline. The mUniquePacketID field serves as a critical identifier for tracking packet delivery status and maintaining cache consistency across the server's networking infrastructure. When an attacker submits a packet with the maximum uint32 value, the server's internal logic interprets this as a request to create cache entries for all missing packet IDs in the range from the last received ID up to the maximum value. This creates a massive memory allocation request that quickly exhausts available system resources, particularly affecting servers running on systems with limited RAM or constrained memory environments.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire server operations and availability. The unbounded memory allocation causes the server process to consume all available memory resources within seconds of receiving the malicious packet, leading to complete system crash and termination. The std::bad_alloc exception that propagates through the codebase ultimately terminates the application process, requiring manual intervention to restart the service. This vulnerability affects gaming servers that rely on Sonic 3 A.I.R.'s networking stack for multiplayer functionality, potentially allowing attackers to perform denial-of-service attacks against competitive gaming environments and online communities.
This vulnerability aligns with CWE-129, which addresses improper validation of array indices and memory allocation bounds, and specifically relates to CWE-704, concerning incorrect type conversion or truncation. The attack vector follows ATT&CK technique T1498, targeting resource exhaustion through network-based attacks that consume system resources. The flaw demonstrates poor defensive programming practices where input validation occurs after memory allocation decisions have been made, creating a classic buffer overflow scenario in the logical domain rather than traditional memory corruption. Organizations running Sonic 3 A.I.R. servers should implement immediate patching strategies and consider implementing rate limiting or packet filtering mechanisms to prevent exploitation attempts while awaiting official security updates.
The root cause of this vulnerability reflects fundamental issues in network protocol implementation design where trust is placed in external data without proper sanitization before processing. The server architecture assumes that incoming packet identifiers will follow expected ranges, but fails to validate that these values remain within reasonable bounds for memory allocation purposes. This pattern of vulnerability commonly occurs in high-performance networking systems where optimization priorities override defensive coding practices. The fix requires implementing explicit bounds checking on the mUniquePacketID field before any memory allocation decisions are made, ensuring that packet identifiers fall within acceptable ranges and preventing the creation of excessively large cache structures that could exhaust system resources during normal operation or malicious exploitation attempts.