CVE-2025-21593

/// Technical description

An Improper Control of a Resource Through its Lifetime vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network-based attacker to cause a Denial-of-Service (DoS).

On devices with SRv6 (Segment Routing over IPv6) enabled, an attacker can send a malformed BGP UPDATE packet which will cause the rpd to crash and restart. Continued receipt of these UPDATE packets will cause a sustained DoS condition. 

This issue affects iBGP and eBGP, and both IPv4 and IPv6 are affected by this vulnerability.This issue affects Junos OS: 

* All versions before 21.2R3-S9, 

* from 21.4 before 21.4R3-S10, 

* from 22.2 before 22.2R3-S5, 

* from 22.3 before 22.3R3-S4, 

* from 22.4 before 22.4R3-S3, 

* from 23.2 before 23.2R2-S2, 

* from 23.4 before 23.4R2;

and Junos OS Evolved: 

* All versions before 21.2R3-S9-EVO, 

* from 21.4-EVO before 21.4R3-S10-EVO, 

* from 22.2-EVO before 22.2R3-S5-EVO, 

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References