External risk intelligence

Juniper Junos OS SRX Heap Overflow Denial of Service Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-101950

The vulnerability exists in Juniper SRX Series firewalls within the Secure Vector Routing (SVR) component. As these devices are typically deployed at the network edge to manage traffic and routing, they are frequently exposed to the public internet to facilitate connectivity, making the network-facing interface reachable by unauthenticated attackers.

Buffer Overflow

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in Juniper Networks' Junos OS, specifically within the Secure Vector Routing component on SRX Series devices. This issue allows for unauthenticated network attackers to potentially disrupt services, compromise data confidentiality, and impact data integrity through specially crafted IPv4 packets. The main concern is confirming relevance and exposure to our environment.

An attacker can disrupt services and data.
Affects network security devices at the internet edge.
Confirm relevance and potential exposure of impacted devices.

Attack Path

How an attacker could exploit the issue

An attacker can exploit this vulnerability by sending specially crafted IPv4 packets over the network to a Juniper SRX Series device. If the device's Secure Vector Routing component is enabled, these packets can trigger a heap-based buffer overflow, potentially leading to denial of service and unauthorized access to sensitive information.

Entry condition: Network accessibility to an interface.
Trigger point: Malformed IPv4 packets to SVR.
Resulting risk: Denial of service, data compromise.

Live Threat

Current exploitation, exposure, and threat context

A heap-based buffer overflow in the SVR component of Juniper Networks Junos OS on SRX Series devices could allow an unauthenticated network attacker to cause a denial of service. This could also potentially compromise the confidentiality and integrity of the system when malformed IPv4 packets reach an interface configured for Secure Vector Routing.

System data and service behavior at risk.
Via malformed IPv4 packets.
Potential loss of confidentiality and integrity.

Operational Fix

Recommended remediation, mitigation, and detection steps

This critical vulnerability in Juniper Networks Junos OS on SRX Series devices requires immediate attention from infrastructure and security teams. The first practical step is to identify all SRX devices running the affected SVR component, determine their exposure to the network, confirm business criticality, and locate the accountable owner for remediation planning.

Ownership: Network and infrastructure teams.
Verify first: Device exposure and SVR reachability.
Action: Plan vendor coordination and remediation.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is Junos OS on Juniper SRX Series devices?

Junos OS is the operating system powering Juniper Networks' SRX Series, which are high-performance security gateways and firewalls. These devices serve as foundational components in network infrastructure, managing traffic flow, enforcing security policies, and routing data between network segments to protect enterprise environments from unauthorized access.

What does a heap-based buffer overflow mean for CVE-2026-101950?

This vulnerability, classified as CWE-122, occurs when the software writes more data to a specific area of memory (the heap) than it can hold. Because this happens in the Secure Vector Routing (SVR) component, a malformed IPv4 packet can overwrite adjacent memory, causing the system to crash or allowing an attacker to bypass security protections to compromise data.

How is the SVR component triggered by an attacker?

An attacker triggers this vulnerability by sending specially crafted, malformed IPv4 packets to a network interface on the device where Secure Vector Routing is actively configured. If SVR is not enabled on a specific interface, that interface is not a valid pathway for this specific exploit condition.

Is my network device at risk according to Halo Surface Signal?

Halo Surface Signal indicates that because SRX Series firewalls are typically deployed at the network edge to manage traffic, their interfaces are often exposed directly to the internet. This frequent public-facing placement makes them reachable by unauthenticated attackers, heightening the risk for any device where the vulnerable SVR component is currently active.

What are the first steps to manage CVE-2026-101950?

Begin by auditing your infrastructure to create a definitive list of all SRX devices running the Secure Vector Routing component. Verify which of these specific units are reachable from the internet or untrusted network segments, determine their business criticality, and coordinate with the accountable network owners to prioritize a remediation plan.

References

supportportal.juniper.net/JSA112186

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.