CVE-2026-76685 in EdgeConnect SD-WAN
Summary
by MITRE • 09/15/2026
A vulnerability exists in the proxy packet processing logic of the affected component where it improperly processes malformed or truncated input. An unauthenticated remote attacker could exploit this vulnerability by providing specially crafted input that triggers an integer overflow. Successful exploitation could result in a buffer overflow, potentially leading to remote code execution or denial-of-service.
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Analysis
by VulDB Data Team • 09/15/2026
The identified security flaw resides within the proxy packet processing logic of the affected component, specifically concerning its handling of malformed or truncated network inputs. This vulnerability stems from a fundamental failure in input validation and boundary checking mechanisms during the parsing phase. When the system receives packets that do not conform to expected structural norms, such as those with unexpected lengths or missing termination sequences, the internal arithmetic operations used to calculate buffer sizes or memory offsets fail to account for these anomalies correctly. Instead of rejecting the invalid data immediately through a safe error handling routine, the component proceeds with calculations based on corrupted length fields or truncated headers. This lack of rigorous sanitization allows an attacker to manipulate the internal state variables that govern memory allocation and access patterns, creating a pathway for severe exploitation against the underlying infrastructure.
At the technical core of this issue is an integer overflow condition triggered by specially crafted input data. When an unauthenticated remote attacker submits packets with specific malformed values in header fields or payload length indicators, the arithmetic operations performed to determine buffer requirements can wrap around due to fixed-width integer limitations. For instance, if a truncated packet specifies a small value that results from wrapping a larger malicious size, the system may allocate significantly less memory than required for processing the actual data content. This discrepancy between allocated and expected memory space creates a classic heap or stack-based buffer overflow scenario. As the proxy attempts to copy the incoming data into the undersized buffer, excess bytes spill over adjacent memory locations, corrupting critical control structures such as return addresses, function pointers, or exception handlers within the application process.
The operational impact of this vulnerability is severe and multifaceted, primarily centering on remote code execution and denial-of-service capabilities. If an attacker successfully exploits the integer overflow to achieve a buffer overflow, they can overwrite memory with shellcode or ROP gadgets designed to hijack the control flow of the proxy service. This allows for arbitrary command execution under the privileges of the compromised process, potentially granting full access to the host system and enabling lateral movement within the network. Even if code execution is not achieved due to modern mitigations like ASLR or DEP, the memory corruption can cause immediate application crashes or instability in dependent services. This leads to a denial-of-service condition where legitimate traffic cannot be processed, disrupting business operations and potentially causing cascading failures across interconnected systems that rely on this proxy for connectivity.
From a classification perspective, this vulnerability aligns with CWE-190 Integer Overflow or Wraparound as the root cause, which subsequently enables CWE-120 Buffer Copy without Checking Size of Input Classic Buffer Overflow. The exploitation vector is categorized under ATT&CK technique T1190 Exploit Public-Facing Application, indicating that attackers can leverage this flaw remotely against internet-facing services. Additionally, the resulting impact falls under MITRE ATT&CK tactic TA0002 Execution and potentially TA0004 Impact if denial-of-service is the primary outcome. The lack of authentication required for exploitation further elevates the risk profile, as any external actor on the network can attempt to trigger this condition without prior credentials or access restrictions.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. Immediate action should involve applying vendor-provided patches that correct the integer arithmetic logic and enforce strict bounds checking during packet parsing. If patching is not immediately feasible, deploying a Web Application Firewall or Intrusion Prevention System with signatures for this specific malformed input pattern can help filter out malicious packets before they reach the vulnerable component. Long-term solutions require implementing secure coding practices such as using safe string handling libraries that prevent buffer overflows and adopting fuzz testing methodologies to identify similar edge cases in packet processing logic. Furthermore, enabling network-level rate limiting and deep packet inspection can reduce the attack surface by detecting anomalous traffic patterns associated with exploitation attempts before they trigger the underlying vulnerability.