CVE-2024-21596Network attack vector

Backup routing-engine crash via crafted BGP UPDATE

Published Jan 12, 2024 · Updated Sep 25, 2024

Heap-based buffer overflow in Juniper Networks Junos OS and Junos OS Evolved allows remote attackers to crash the backup RPD. A specific BGP UPDATE received over an established eBGP or iBGP session overwrites heap memory, crashing and restarting RPD on the backup Routing Engine. Only NSR-enabled devices are affected; repeated messages sustain the backup-engine outage, while the primary engine and traffic remain unaffected.

CVSS severity5.3
Medium
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in Juniper Networks Junos OS and Junos OS Evolved allows remote attackers to crash the backup RPD. A specific BGP UPDATE received over an established eBGP or iBGP session overwrites heap memory, crashing and restarting RPD on the backup Routing Engine. Only NSR-enabled devices are affected; repeated messages sustain the backup-engine outage, while the primary engine and traffic remain unaffected.

The record

CVE
CVE-2024-21596
Published
Jan 12, 2024
Updated
Sep 25, 2024
Vendor
Juniper Networks
Product
Junos OS Evolved
Classifications
CWE-122, CWE-787, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 12, 2024CVE publishedPublication date reported by the CVE source.
  2. Sep 25, 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-EVO <21.4R3-S5-EVO
  3. Affected versionversion=22.1-EVO <22.1R3-S4-EVO
  4. Affected versionversion=22.2-EVO <22.2R3-S2-EVO
  5. Affected versionversion=22.4-EVO <22.4R2-S2-EVO, 22.4R3-EVO
  6. Affected versionversion=23.1-EVO <23.1R2-EVO
  7. Affected versionversion=23.2-EVO <23.2R1-S2-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-EVO <21.4R3-S5-EVO; version=22.1-EVO <22.1R3-S4-EVO; version=22.2-EVO <22.2R3-S2-EVO; version=22.4-EVO <22.4R2-S2-EVO, 22.4R3-EVO; version=23.1-EVO <23.1R2-EVO; version=23.2-EVO <23.2R1-S2-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-S2; version=22.3 <22.3R3-S1; version=22.4 <22.4R2-S2, 22.4R3; version=23.1 <23.1R2; version=23.2 <23.2R1-S2, 23.2R2

Published CVSS scores

5.3Juniper Networks, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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-122Heap-based Buffer Overflow
CWE-787Out-of-bounds Write
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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