CVE-2025-21599 Denial of service in Junos OS Evolved
Unauthenticated attackers can cause kernel memory exhaustion and system crashes by sending malformed IPv6 packets to Junos OS Evolved devices.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-21599?
CVE-2025-21599 is a high-severity denial of service vulnerability in Juniper Junos Os Evolved, published on 9 Jan 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A Missing Release of Memory after Effective Lifetime vulnerability in the Juniper Tunnel Driver (jtd) of Juniper Networks Junos OS Evolved allows an unauthenticated network-based attacker to cause Denial of Service.
Receipt of specifically malformed IPv6 packets, destined to the device, causes kernel memory to not be freed, resulting in memory exhaustion leading to a system crash and Denial of Service (DoS). Continuous receipt and processing of these packets will continue to exhaust kernel memory, creating a sustained Denial of Service (DoS) condition. This issue only affects systems configured with IPv6.
This issue affects Junos OS Evolved:
* from 22.4-EVO before 22.4R3-S5-EVO, * from 23.2-EVO before 23.2R2-S2-EVO, * from 23.4-EVO before 23.4R2-S2-EVO, * from 24.2-EVO before 24.2R1-S2-EVO, 24.2R2-EVO.
This issue does not affect Juniper Networks Junos OS Evolved versions prior to 22.4R1-EVO.
Weakness: CWE-401
Which versions are affected by CVE-2025-21599?
It affects 1 product.
Products include Juniper Junos Os Evolved.
How do I fix CVE-2025-21599?
No fix has been published for CVE-2025-21599 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-21599 being exploited?
There is no known exploitation of CVE-2025-21599 in the wild and no public exploit code.
Other vulnerabilities in Juniper Junos Os Evolved
- CVE-2026-21902 Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root
- CVE-2023-28983 Junos OS Evolved: Shell Injection vulnerability in the gNOI server
- CVE-2024-47502 Junos OS Evolved: TCP session state is not always cleared on the Routing Engine leading to DoS
- CVE-2024-39531 Junos OS Evolved: ACX 7000 Series: Protocol specific DDoS configuration affects other protocols
- CVE-2024-39562 Junos OS Evolved: A high rate of SSH connections causes a Denial of Service
Sources
Also known as GHSA-p34f-rw7f-c723.