Vulnerability in Juniper Junos
CVE-2025-21597
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.002 (14.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 14th percentile — 14.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
Affected products
- Juniper Junos — versions 20.4, 21.2, 21.3
- Juniper Junos OS Evolved — versions 21.2, 21.3, 21.4
- Juniper Networks Junos OS — versions 0, 21.2, 21.3
- Juniper Networks Junos OS Evolved — versions 0, 21.3-EVO, 21.4-EVO
Weakness classification (CWE)
References
- kb.juniper.net/JSA96451 (vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2025-21597?
- CVE-2025-21597 is a medium-severity vulnerability in Juniper Junos, classified under Improper Check for Unusual or Exceptional Conditions. CVSS score: 5.3/10. Published 2025-04-09.
- How severe is CVE-2025-21597?
- Medium severity. CVSS v3 base score is 5.3 out of 10.