CVE-2026-121511 in Ud3tn
Summary
by MITRE • 11/03/2026
Heap Out-of-Bounds Read in µD3TN BPv6/BPv7 Fragmenter allows Local Attacker to Read Memory and Reliably Cause DoS
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as a heap out-of-bounds read within the µD3TN Bundle Protocol version 6 or version 7 fragmenter represents a critical memory safety flaw that compromises both data confidentiality and system availability. This specific component is responsible for managing the segmentation and reassembly of large bundle protocol messages, a process essential for reliable communication over lossy or high-latency networks typical in Delay-Tolerant Networking environments. The defect arises from an improper validation of length fields or index calculations during the processing of fragmented packets, allowing an attacker to trigger memory access operations that extend beyond the allocated heap boundaries. Because this vulnerability is exploitable by a local attacker, it implies that any user account with sufficient privileges to interact with the network stack or inject crafted bundle protocol payloads can leverage this flaw against the host system.
From a technical perspective, the core issue lies in the fragmenter's failure to strictly enforce bounds checking when calculating offsets into heap-allocated buffers. When a malformed packet containing specific length values is processed, the application may attempt to read data from memory addresses that are not part of the intended buffer structure. This out-of-bounds read does not necessarily result in immediate code execution but provides the attacker with the ability to leak sensitive information stored adjacent to the heap allocation. Such leaked data can include cryptographic keys, session tokens, or other internal state variables, thereby facilitating further attacks such as privilege escalation or session hijacking. Furthermore, depending on how the operating system handles memory access violations and whether specific mitigations like stack canaries are bypassed through subsequent operations, this read operation can lead to unpredictable behavior that crashes the application or the entire network service daemon.
The operational impact of this vulnerability is twofold, encompassing both information disclosure and denial of service. The ability to reliably cause a Denial of Service means that an attacker can disrupt critical networking services by forcing the system into an error state or crash loop through repeated exploitation attempts. This is particularly damaging in environments where continuous connectivity is required for mission-critical operations, such as aerospace communications or remote infrastructure monitoring. Simultaneously, the memory read capability undermines the confidentiality guarantees expected from secure network protocols. By extracting arbitrary heap contents, the attacker gains insights into the internal workings of the system, which can be used to craft more sophisticated attacks that bypass security controls designed for known vulnerabilities but remain blind to these low-level memory corruption issues.
This vulnerability aligns with Common Weakness Enumeration category CWE-125, Out-of-bounds Read, and is also associated with CWE-400 Uncontrolled Resource Consumption if the exploitation leads to resource exhaustion or system instability. In terms of offensive security frameworks, this flaw maps to MITRE ATT&CK technique T1083 File and Directory Discovery when used for information gathering, although its primary classification remains within memory corruption vulnerabilities that facilitate lateral movement or privilege escalation in subsequent stages of an attack chain. The local nature of the exploit highlights the importance of principle of least privilege, as restricting user access to network configuration tools can mitigate the risk of initial exploitation.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Developers should immediately apply patches that enforce strict bounds checking in the fragmenter logic, ensuring that all memory accesses are validated against allocated buffer sizes before execution. Static analysis tools configured with high sensitivity to heap corruption issues can help identify similar flaws in related code paths. For system administrators, implementing network segmentation to limit local access to critical networking daemons and applying runtime protection mechanisms such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) can reduce the likelihood of successful exploitation or mitigate its impact by making memory layout unpredictable and preventing execution of injected payloads. Regular security audits focusing on C/C++ codebases are essential to prevent recurrence, given that manual review is often required to catch subtle off-by-one errors in complex protocol implementations.