CVE-2026-101950 in Junos OS
Summary
by MITRE • 10/14/2026
A Heap-based Buffer Overflow vulnerability in the SVR component of Juniper Networks Junos OS on SRX Series allows an unauthenticated network attacker to cause a denial of service and potentially compromise confidentiality and integrity via malformed IPv4 packets reaching an interface configured for Secure Vector Routing.
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Analysis
by VulDB Data Team • 10/14/2026
The identified vulnerability represents a critical security flaw within the SVR component of Juniper Networks Junos OS, specifically affecting devices in the SRX Series firewall family. This heap-based buffer overflow arises from improper memory management practices when processing incoming network traffic. The root cause lies in the failure to adequately validate or bound-check data lengths associated with IPv4 packets before they are copied into a pre-allocated heap buffer. When an attacker crafts and transmits malformed IPv4 packets containing oversized payload fields, the SVR module attempts to process this input without verifying that it fits within the allocated memory space. This lack of rigorous boundary checking allows external data to overwrite adjacent memory locations on the heap, leading to corruption of critical program structures such as function pointers or object metadata stored in nearby allocations.
From an operational perspective, the immediate impact of exploiting this vulnerability is a denial of service condition. The memory corruption typically causes the SVR process or the underlying operating system kernel to crash, resulting in a loss of connectivity and availability for the firewall device. However, given that heap overflows provide significant control over program execution flow if specific conditions are met, such as predictable memory layout and available exploitation primitives like arbitrary write capabilities, the risk extends far beyond simple service disruption. An unauthenticated attacker positioned on the network segment connected to an interface configured for Secure Vector Routing can leverage this flaw to execute arbitrary code with the privileges of the affected process. This potential compromise threatens both the confidentiality and integrity of the system, as successful exploitation could allow the insertion of backdoors, data exfiltration, or lateral movement within the protected network infrastructure.
This vulnerability aligns closely with CWE-122, which describes a heap-based buffer overflow where an application writes more data to a heap-allocated buffer than it can hold. The attack vector is classified under ATT&CK technique T1498, Network Denial of Service, due to the potential for service disruption through resource exhaustion or system crashes. Furthermore, if code execution is achieved, it relates to techniques involving memory corruption and privilege escalation within the network device environment. The requirement that the interface be configured for Secure Vector Routing indicates a specific attack surface exposure, meaning defenders must ensure that this feature is disabled on interfaces facing untrusted networks unless absolutely necessary, thereby reducing the potential entry points for such malformed packet attacks.
Mitigation strategies should prioritize immediate patching to the latest version of Junos OS where this heap overflow has been remediated through improved input validation and bounds checking in the SVR module. In environments where upgrading is not immediately feasible, network segmentation policies must be enforced to restrict access to SRX interfaces configured for Secure Vector Routing from untrusted or public networks. Additionally, implementing ingress filtering on upstream routers can help drop malformed IPv4 packets before they reach the vulnerable device. Security operations teams should monitor for anomalous traffic patterns indicative of fuzzing attempts or repeated connection resets associated with SVR services, as these may signal active exploitation attempts against this specific vulnerability in the wild.