CVE-2026-103410 in Session Smart Router
Summary
by MITRE • 10/28/2026
An Integer Overflow vulnerability in the DPI certificate scanner in Juniper Networks Session Smart Router allows an unauthenticated remote attacker to cause a denial of service via a specially crafted TLS server certificate.
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Analysis
by VulDB Data Team • 10/28/2026
The identified vulnerability resides within the Deep Packet Inspection (DPI) module, specifically affecting the certificate scanning functionality of the Juniper Networks Session Smart Router. This component is responsible for inspecting network traffic to enforce security policies and identify applications or threats based on packet content. The flaw manifests as an integer overflow during the parsing and validation processes associated with Transport Layer Security (TLS) server certificates. When a remote, unauthenticated attacker submits a specially crafted TLS certificate containing malformed data structures that trigger arithmetic errors exceeding the allocated memory bounds for integer variables, it disrupts the normal execution flow of the DPI engine. This type of vulnerability is classically categorized under CWE-190, which defines Integer Overflow or Wraparound as a weakness where an arithmetic operation results in a value larger than what can be represented by the data type, leading to unpredictable behavior such as buffer overflows, logic errors, or system crashes.
From an operational perspective, this vulnerability poses a significant risk of denial of service against the Session Smart Router infrastructure. Because the flaw is triggered during certificate inspection, which occurs early in the TLS handshake process for encrypted traffic, it can be exploited by any external entity attempting to establish a secure connection through the router without requiring prior authentication credentials. The successful exploitation results in the termination or severe degradation of the DPI service, effectively blinding the security appliance to inspecting subsequent traffic. This disruption allows malicious actors to bypass inspection mechanisms and potentially exfiltrate data or launch further attacks undetected. In terms of adversary tactics, this aligns with ATT&CK technique T1498, Network Denial of Service, where an attacker aims to disrupt availability by exhausting resources or crashing services rather than compromising confidentiality or integrity directly at the point of exploitation.
The severity of this issue is compounded by its remote and unauthenticated nature, meaning that no valid user account or prior network access is required to trigger the crash. Attackers can automate the generation of malicious certificates using standard cryptographic libraries to probe for vulnerable instances across public-facing interfaces. The impact extends beyond simple service interruption; if the DPI engine fails repeatedly, it may cause broader instability in the router's control plane depending on how error handling and recovery mechanisms are implemented within the specific firmware version affected. This could lead to a complete loss of management connectivity or policy enforcement capabilities for the entire network segment protected by the Session Smart Router.
Mitigation strategies must prioritize immediate patching through official Juniper Networks security advisories, as software updates typically include fixes that validate input lengths and enforce strict bounds checking on integer arithmetic operations during certificate parsing. Until patches are applied, administrators should consider implementing network-level access control lists to restrict TLS traffic from untrusted sources or disabling specific DPI inspection profiles for external-facing interfaces if feasible without compromising critical business functions. Additionally, deploying a Web Application Firewall or next-generation intrusion prevention system upstream of the router can help filter out malformed packets before they reach the vulnerable component, providing an additional layer of defense against exploitation attempts targeting this integer overflow condition.