CVE-2024-21585Network attack vector

Routing denial of service via parallel BGP replication

Published Jan 12, 2024 · Updated Nov 14, 2024

Improper exception handling in Junos OS and Junos OS Evolved allows remote attackers to crash and restart rpd through BGP session flaps. When a session returns while GR or LLGR stale-route replication is still running, rpd starts unsolicited replication for the same peer without first cleaning up the existing replication, and a later flap triggers an assertion. No authentication is required, but exploitation requires NSR, GR-helper mode, a peer that negotiated restarter capability, and timing outside attacker control; repeated flaps sustain the routing outage.

CVSS severity8.2
High
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper exception handling in Junos OS and Junos OS Evolved allows remote attackers to crash and restart rpd through BGP session flaps. When a session returns while GR or LLGR stale-route replication is still running, rpd starts unsolicited replication for the same peer without first cleaning up the existing replication, and a later flap triggers an assertion. No authentication is required, but exploitation requires NSR, GR-helper mode, a peer that negotiated restarter capability, and timing outside attacker control; repeated flaps sustain the routing outage.

The record

CVE
CVE-2024-21585
Published
Jan 12, 2024
Updated
Nov 14, 2024
Vendor
Juniper Networks
Product
Junos OS Evolved
Classifications
CWE-755, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 12, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 14, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0 <21.3R3-S5-EVO
  2. Affected versionversion=21.4 <21.4R3-S5-EVO
  3. Affected versionversion=22.1 <22.1R3-S4-EVO
  4. Affected versionversion=22.2 <22.2R3-S3-EVO
  5. Affected versionversion=22.3 <22.3R3-S1-EVO
  6. Affected versionversion=22.4 <22.4R2-S2-EVO, 22.4R3-EVO
  7. Affected versionversion=23.2 <23.2R1-S1-EVO, 23.2R2-EVO

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OS Evolvedversion=0 <21.3R3-S5-EVO; version=21.4 <21.4R3-S5-EVO; version=22.1 <22.1R3-S4-EVO; version=22.2 <22.2R3-S3-EVO; version=22.3 <22.3R3-S1-EVO; version=22.4 <22.4R2-S2-EVO, 22.4R3-EVO; version=23.2 <23.2R1-S1-EVO, 23.2R2-EVO
Juniper Networks · Junos OSversion=0 <20.4R3-S9; version=21.2 <21.2R3-S7; version=21.3 <21.3R3-S5; version=21.4 <21.4R3-S5; version=22.1 <22.1R3-S4; version=22.2 <22.2R3-S3; version=22.3 <22.3R3-S1; version=22.4 <22.4R2-S2, 22.4R3; version=23.2 <23.2R1-S1, 23.2R2

Published CVSS scores

8.2Juniper NetworksCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L
7.5Juniper NetworksCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
T1499.004Application or System Exploitation

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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