CVE-2026-102062 in Junos OS
Summary
by MITRE • 10/14/2026
An Use of Externally-Controlled Format String vulnerability in the ipfd daemon of Juniper Networks Junos OS on SRX Series allows an unauthenticated network-based attacker to execute code with root privileges via a compromised or impersonated configured HTTPS feed server.
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Analysis
by VulDB Data Team • 10/14/2026
The identified vulnerability represents a critical security flaw within the Internet Protocol Flow Data (IPFD) daemon, which is a core component of Juniper Networks Junos OS running on SRX Series firewalls. This specific weakness falls under the category of Use of Externally-Controlled Format String, commonly referenced in industry standards as CWE-134. The root cause lies in how the IPFD service processes data received from configured HTTPS feed servers. When the daemon receives formatted strings or log entries from these external sources without proper sanitization or validation, it passes them directly to format string functions such as printf or syslog with user-controlled input acting as the format argument. This architectural oversight allows an attacker who controls or impersonates a trusted HTTPS feed server to inject maliciously crafted format specifiers into the data stream.
From an operational perspective, this vulnerability is particularly severe because it enables unauthenticated remote code execution with root privileges. The IPFD daemon typically operates with elevated system permissions to facilitate network monitoring and flow analysis. By exploiting the format string flaw, an attacker can manipulate memory operations on the stack or heap. This manipulation can lead to arbitrary read/write capabilities, allowing the extraction of sensitive information from process memory or the overwriting of critical function pointers and return addresses. Consequently, this leads to the execution of arbitrary code within the context of the root user, effectively granting full control over the compromised firewall device. The attack vector is network-based, meaning it can be exploited remotely without requiring prior authentication on the target system, provided that a malicious HTTPS feed server is configured or impersonated in the network path.
The impact of this vulnerability extends beyond simple code execution to include potential denial of service and complete compromise of network security posture. An attacker gaining root access can disable logging mechanisms, alter firewall rules to allow unauthorized traffic, exfiltrate sensitive network data, or use the compromised device as a pivot point for further attacks against internal networks. This undermines the fundamental purpose of the SRX Series devices, which is to serve as a trusted boundary between different security zones. The reliance on external HTTPS feed servers introduces a supply chain risk where trust in third-party services becomes a single point of failure if those services are compromised or spoofed via techniques such as DNS hijacking or man-in-the-middle attacks that bypass certificate validation checks during the initial connection phase.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The primary defense is to apply the vendor-provided software patches that update the IPFD daemon to versions where input sanitization has been implemented for format string handling. Organizations should ensure their Junos OS installations are kept up-to-date with the latest security advisories released by Juniper Networks. In addition to patching, network segmentation and strict access control lists (ACLs) should be employed to restrict which hosts can communicate with the HTTPS feed servers used by the SRX devices. Implementing mutual TLS authentication for these feeds ensures that only verified and trusted sources can provide data, thereby preventing impersonation attacks. Furthermore, monitoring systems should be configured to detect anomalous behavior in log processing or unexpected privilege escalations within the IPFD process as an indicator of potential exploitation attempts.
This vulnerability aligns with several MITRE ATT&CK techniques related to initial access and privilege escalation. Specifically, it relates to T1078 Valid Accounts if the attacker compromises a feed server credential, and more critically to T1203 Exploitation for Client Execution or T1059 Command and Scripting Interpreter through the format string exploitation mechanism. The ability to execute code as root maps directly to privilege escalation tactics where an adversary leverages system vulnerabilities to gain higher-level permissions. Understanding these mappings helps security teams prioritize detection rules based on known attacker behaviors associated with this class of flaws, ensuring that even if a patch is delayed, monitoring controls can provide compensatory protection against active exploitation attempts targeting the IPFD service.