CVE-2026-121513 in µD3TN
Summary
by MITRE • 11/03/2026
Off-by-one Heap Overflow in µD3TN v0.15.1 SPP Parser allows Unauthenticated Remote Attacker to Reliably Cause DoS
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as an off-by-one heap overflow within the Simple Protocol Parser (SPP) of µD3TN version 0.15.1 represents a critical memory corruption flaw that stems from improper boundary checking during data parsing operations. This specific implementation error occurs when the parser processes incoming network packets, failing to correctly account for null terminators or length fields associated with string buffers allocated on the heap. Consequently, the application writes one byte beyond the intended buffer limit, overwriting adjacent memory structures. In the context of embedded systems and IoT devices utilizing this library, such as those adhering to DTN (Delay-Tolerant Networking) standards, the SPP is often responsible for handling control messages that dictate routing and session management behaviors. The lack of rigorous input validation allows an unauthenticated remote attacker to craft maliciously sized packets that trigger this memory overwrite condition reliably upon receipt by the target device.
From a technical perspective, heap overflows are particularly dangerous because they corrupt metadata structures managed by the dynamic memory allocator rather than just application data. In many modern operating environments and embedded RTOS implementations, adjacent heap chunks contain size fields or pointers to other allocated blocks. Overwriting these control structures can lead to immediate instability in the memory management subsystem. While the primary reported impact is a Denial of Service (DoS), characterized by application crashes or system reboots due to segmentation faults triggered by corrupted pointer dereferences later in execution, this type of vulnerability inherently carries significant risk for arbitrary code execution if exploited with precise timing and heap grooming techniques. The reliability mentioned in the description suggests that the overflow condition is deterministic based on specific packet structures, making it a high-confidence attack vector against devices running this version of µD3TN without requiring prior authentication or complex privilege escalation steps.
The operational impact of this vulnerability extends beyond simple service interruption. For IoT deployments relying on DTN protocols for asynchronous communication in disconnected or intermittently connected environments, such as industrial control systems or remote telemetry networks, a reliable DoS capability effectively blinds the network node to incoming commands and status updates. This can lead to significant downtime in critical infrastructure where continuous monitoring is required. Furthermore, because the vulnerability exists within a core networking library used by multiple applications potentially running on the same device, compromising this component could serve as an initial foothold for lateral movement or further exploitation of other services hosted on the embedded platform. The unauthenticated nature of the attack means that any host with network connectivity to the vulnerable device can attempt exploitation, significantly expanding the attack surface in public-facing or poorly segmented private networks.
Mitigation strategies must prioritize immediate patching if an updated version of µD3TN is available from the vendor, as this addresses the root cause within the source code by implementing strict bounds checking and proper length validation before memory allocation and copy operations. In scenarios where patching is not immediately feasible due to certification or deployment constraints, network-level defenses should be employed to filter incoming traffic destined for the SPP service ports. Intrusion detection systems can be configured with signatures that detect anomalous packet lengths or malformed headers characteristic of this specific overflow trigger. Additionally, enabling Address Space Layout Randomization (ASLR) and stack canaries on devices running vulnerable firmware can increase the difficulty of successful exploitation by randomizing memory addresses and detecting corruption attempts before they lead to code execution, although these mitigations do not prevent the initial DoS condition caused by the crash itself.
This vulnerability aligns with Common Weakness Enumeration identifier CWE-193, which describes an off-by-one error leading to a buffer overflow, specifically in this case affecting heap memory rather than stack or static data segments. The exploitation technique maps closely to MITRE ATT&CK tactic T1498, Network Denial of Service, as the primary observed effect is the disruption of normal system operations through resource exhaustion via crash-inducing inputs. Understanding these mappings helps security teams categorize the risk accurately within their vulnerability management programs and prioritize remediation efforts based on both technical severity and business impact. Continuous monitoring for unusual network traffic patterns targeting DTN services can provide early warning indicators of exploitation attempts, allowing for rapid incident response before widespread service disruption occurs across affected deployments.