Description

An Improper Check for Unusual or Exceptional Conditions vulnerability in routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, logically adjacent BGP peer to cause Denial of Service (DoS).

On all Junos OS and Junos OS Evolved platforms, when BGP rib-sharding and update-threading are configured, and a BGP peer flap is done with specific timing, rpd crashes and restarts. Continuous peer flapping at specific time intervals will result in a sustained Denial of Service (DoS) condition.

This issue affects eBGP and iBGP, in both IPv4 and IPv6 implementations. This issue requires a remote attacker to have at least one established BGP session. The issue can occur with or without logical-systems enabled.

This issue affects:
Junos OS:

* All versions before 20.4R3-S8,
* 21.2 versions before 21.2R3-S6,

* 21.3 versions before 21.3R3-S5,
* 21.4 versions before 21.4R3-S4,
* 22.1 versions before 22.1R3-S3,
* 22.2 versions before 22.2R3-S1,
* 22.3 versions before 22.3R3,
* 22.4 versions before 22.4R3.

Junos OS Evolved:

* All versions before 21.2R3-S6-EVO,
* 21.3-EVO versions before 21.3R3-S5-EVO,
* 21.4-EVO versions before 21.4R3-S4-EVO,
* 22.1-EVO versions before 22.1R3-S3-EVO,
* 22.2-EVO versions before :22.2R3-S1-EVO,
* 22.3-EVO versions before 22.3R3-EVO,
* 22.4-EVO versions before 22.4R3-EVO.

Classification

CVE ID: CVE-2025-21597

CVSS Base Severity: MEDIUM

CVSS Base Score: 5.3

CVSS Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Products

Vendor: Juniper Networks, Juniper Networks

Product: Junos OS, Junos OS Evolved

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.06% (probability of being exploited)

EPSS Percentile: 17.4% (scored less or equal to compared to others)

EPSS Date: 2025-04-21 (when was this score calculated)

References

https://nvd.nist.gov/vuln/detail/CVE-2025-21597
https://kb.juniper.net/JSA96451

Timeline