CVE-2025-21599

Junos OS Evolved: Receipt of specifically malformed IPv6 packets causes kernel memory exhaustion leading to Denial of Service

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.

Remediation

Solution:

  • The following software releases have been updated to resolve this specific issue: Junos OS Evolved: 22.4R3-S5-EVO, 23.2R2-S2-EVO, 23.4R2-S2-EVO, 24.2R1-S2-EVO, 24.2R2-EVO*, 24.4R1-EVO, and all subsequent releases. * Future Release

Workaround:

  • There are no known workarounds for this issue.

Category

8.7
CVSS
Severity: High
CVSS 4.0 •
CVSS 3.1 •
EPSS 0.14%
Vendor Advisory juniper.net
Affected: Juniper Networks Junos OS Evolved
Published at:
Updated at:

References

Frequently Asked Questions

What is the severity of CVE-2025-21599?
CVE-2025-21599 has been scored as a high severity vulnerability.
How to fix CVE-2025-21599?
To fix CVE-2025-21599: The following software releases have been updated to resolve this specific issue: Junos OS Evolved: 22.4R3-S5-EVO, 23.2R2-S2-EVO, 23.4R2-S2-EVO, 24.2R1-S2-EVO, 24.2R2-EVO*, 24.4R1-EVO, and all subsequent releases. * Future Release
Is CVE-2025-21599 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2025-21599 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-21599?
CVE-2025-21599 affects Juniper Networks Junos OS Evolved.
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