External risk intelligence

Juniper Junos OS SRX Use of Externally-Controlled Format String Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.2)

CVE-2026-102062

The vulnerability exists in the ipfd daemon of Juniper Junos OS on SRX Series devices, specifically involving interactions with configured HTTPS feed servers. While these devices are often internet-facing, this specific attack vector requires the attacker to compromise or impersonate a configured external HTTPS feed server that the device communicates with, rather than directly attacking the device's own public interface.

Halo Surface Signal: 3 out of 5 — possibly public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory highlights a critical vulnerability within the Juniper Networks Junos OS on SRX Series devices, specifically affecting the ipfd daemon. The issue could allow an unauthenticated attacker to execute code with root privileges by compromising or impersonating a configured HTTPS feed server. This warrants careful consideration regarding the security posture of affected systems and their communication channels.

Attackers could gain root access through compromised servers.
Important for network infrastructure security.
Assess potential exposure and impact.

Attack Path

How an attacker could exploit the issue

An attacker could gain root-level code execution by targeting the ipfd daemon on Juniper Networks SRX Series devices. This is achieved by compromising or impersonating a configured HTTPS feed server, which the device then interacts with. The vulnerability stems from how the daemon handles externally controlled format strings.

Attacker must impersonate a trusted feed server.
Device retrieves malicious content from the server.
Leads to unauthenticated root code execution.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an unauthenticated attacker to execute code with root privileges on affected Juniper Networks SRX Series devices. This is possible when the device is configured to fetch updates from an HTTPS feed server, and the attacker can compromise or impersonate that server.

Root code execution on network devices.
Impersonating a trusted HTTPS feed server.
Compromised network device functionality.

Operational Fix

Recommended remediation, mitigation, and detection steps

This critical vulnerability in Juniper Networks Junos OS SRX Series affects the ipfd daemon and requires immediate attention from infrastructure and security teams. The first step is to identify all SRX Series devices that use configured HTTPS feed servers, confirm their exposure to the internet or trusted internal networks, and determine which devices are business-critical. Once accountable owners are identified, a remediation plan should be developed based on the assessed risk.

Infrastructure and Security teams own remediation.
Verify SRX HTTPS feed server configurations.
Plan risk-based remediation and vendor coordination.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is the ipfd daemon in Juniper Junos OS?

The ipfd daemon is a background process within Juniper Networks Junos OS on SRX Series devices. It is responsible for handling various network management and control functions, including managing communications with external servers. In this context, it specifically manages interactions with HTTPS feed servers used for system updates or data feeds.

What does CWE-134 mean for CVE-2026-102062?

CWE-134 refers to a 'Use of Externally-Controlled Format String' weakness. This means the software takes data from an untrusted source and uses it as a template for formatting text without proper validation. In CVE-2026-102062, this flaw allows an attacker to manipulate the program's memory, which can lead to the unauthorized execution of code with root-level privileges.

How does an attacker trigger this vulnerability?

An attacker must successfully compromise or impersonate a trusted HTTPS feed server that the SRX device is specifically configured to contact. The vulnerability is not triggered by directly sending malicious traffic to the device's standard public interfaces; instead, it occurs when the device pulls and processes malicious content from an external server it expects to be legitimate.

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

Halo Surface Signal identifies this as a 'Possible' risk. While SRX devices are often exposed to the internet, the threat specifically requires a man-in-the-middle or server-compromise scenario involving your configured HTTPS feeds. Evaluate your device's connection to external feed servers, as this is the primary path an attacker must exploit to interact with the vulnerable daemon.

How should I respond to this vulnerability?

Start by identifying all SRX Series devices in your infrastructure that are configured to retrieve data from external HTTPS feed servers. Verify the security of those feed connections and coordinate with your internal teams to assess which devices are business-critical. Develop a risk-based remediation plan that prioritizes these devices while monitoring official vendor updates for further instructions.

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.