CVE-2025-21597

Routing-process crash via timed BGP peer flaps

Published Apr 9, 2025 · Updated Apr 10, 2025

Denial of service in Junos OS and Junos OS Evolved allows remote attackers with a BGP session to crash and restart rpd through timed peer flaps. With BGP rib-sharding and update-threading configured, rpd mishandles an exceptional state during specifically timed peer transitions. An established eBGP or iBGP session over IPv4 or IPv6 is required; repeated flaps sustain the routing-process interruption.

CVSS severity5.3
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Junos OS and Junos OS Evolved allows remote attackers with a BGP session to crash and restart rpd through timed peer flaps. With BGP rib-sharding and update-threading configured, rpd mishandles an exceptional state during specifically timed peer transitions. An established eBGP or iBGP session over IPv4 or IPv6 is required; repeated flaps sustain the routing-process interruption.

The record

CVE
CVE-2025-21597
Published
Apr 9, 2025
Updated
Apr 10, 2025
Vendor
Juniper Networks
Product
Junos OS Evolved
Classifications
CWE-754, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 10, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <21.2R3-S6-EVO
  2. Affected versionversion=21.3-EVO <21.3R3-S5-EVO
  3. Affected versionversion=21.4-EVO <21.4R3-S4-EVO
  4. Affected versionversion=22.1-EVO <22.1R3-S3-EVO
  5. Affected versionversion=22.2-EVO <22.2R3-S1-EVO
  6. Affected versionversion=22.3-EVO <22.3R3-EVO
  7. Affected versionversion=22.4-EVO <22.4R3-EVO

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OS Evolvedversion=0 <21.2R3-S6-EVO; version=21.3-EVO <21.3R3-S5-EVO; version=21.4-EVO <21.4R3-S4-EVO; version=22.1-EVO <22.1R3-S3-EVO; version=22.2-EVO <22.2R3-S1-EVO; version=22.3-EVO <22.3R3-EVO; version=22.4-EVO <22.4R3-EVO
Juniper Networks · Junos OSversion=0 <20.4R3-S8; version=21.2 <21.2R3-S6; version=21.3 <21.3R3-S5; version=21.4 <21.4R3-S4; version=22.1 <22.1R3-S3; version=22.2 <22.2R3-S1; version=22.3 <22.3R3; version=22.4 <22.4R3

Published CVSS scores

5.3Juniper NetworksCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
6.0Juniper NetworksCVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/R:A

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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