Highly exploitable, CVE-2026-21913 poses a critical security risk that could lead to severe breaches.
Status: Received on 15 Jan 2026, 21:16 UTC
Published on: 15 Jan 2026, 21:16 UTC
CVSS Release: version 3
sirt@juniper.net
Primary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVE-2026-21913: An Incorrect Initialization of Resource vulnerability in the Internal Device Manager (IDM) of Juniper Networks Junos OS on EX4000 models allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). On EX4000 models with 48 ports (EX4000-48T, EX4000-48P, EX4000-48MP) a high volume of traffic destined to the device will cause an FXPC crash and restart, which leads to a complete service outage until the device has automatically restarted. The following reboot reason can be seen in the output of 'show chassis routing-engine' and as a log message: reason=0x4000002 reason_string=0x4000002:watchdog + panic with core dump This issue affects Junos OS on EX4000-48T, EX4000-48P and EX4000-48MP: * 24.4 versions before 24.4R2, * 25.2 versions before 25.2R1-S2, 25.2R2. This issue does not affect versions before 24.4R1 as the first Junos OS version for the EX4000 models was 24.4R1.
The exploitability of CVE-2026-21913 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
With low attack complexity and no required privileges, CVE-2026-21913 is an easy target for cybercriminals. Organizations should prioritize immediate mitigation measures to prevent unauthorized access and data breaches.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2026-21913, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2026-21913, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
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