CVE-2024-21611

7.5 HIGH

📋 TL;DR

A memory leak vulnerability in Juniper's Routing Protocol Daemon (rpd) allows unauthenticated network attackers to cause denial of service. When BGP next hops update during Juniper Flow Monitoring (jflow) route churn, memory isn't properly released, eventually crashing rpd. This affects Junos OS 21.4-22.2 and Junos OS Evolved 21.4-EVO to 22.2-EVO before specific patch versions.

💻 Affected Systems

Products:
  • Juniper Junos OS
  • Juniper Junos OS Evolved
Versions: Junos OS: 21.4 earlier than 21.4R3, 22.1 earlier than 22.1R3, 22.2 earlier than 22.2R3. Junos OS Evolved: 21.4-EVO earlier than 21.4R3-EVO, 22.1-EVO earlier than 22.1R3-EVO, 22.2-EVO earlier than 22.2R3-EVO.
Operating Systems: Junos OS, Junos OS Evolved
Default Config Vulnerable: ⚠️ Yes
Notes: Requires jflow configuration and BGP route churn to trigger the memory leak.

📦 What is this software?

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

Junos by Juniper

Junos OS is Juniper Networks' flagship network operating system running on enterprise routers, switches, security appliances, and data center infrastructure worldwide. Deployed across telecommunications providers, ISPs, cloud service providers, financial institutions, and large enterprises, Junos po...

Learn more about Junos →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete routing service disruption requiring manual intervention, potentially affecting network availability across multiple systems.

🟠

Likely Case

Gradual performance degradation leading to rpd crashes and restarts, causing intermittent routing instability.

🟢

If Mitigated

Minimal impact with proper monitoring and quick restart capabilities.

🌐 Internet-Facing: HIGH
🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No
Weaponized: UNKNOWN
Unauthenticated Exploit: ⚠️ Yes
Complexity: MEDIUM

Exploitation requires ability to trigger BGP route churn in jflow scenarios.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Junos OS: 21.4R3, 22.1R3, 22.2R3. Junos OS Evolved: 21.4R3-EVO, 22.1R3-EVO, 22.2R3-EVO.

Vendor Advisory: https://supportportal.juniper.net/JSA75752

Restart Required: Yes

Instructions:

1. Download appropriate patch version from Juniper support portal. 2. Apply patch using 'request system software add' command. 3. Reboot system to complete installation.

🔧 Temporary Workarounds

Monitor memory usage

all

Regularly check rpd memory usage to detect leaks early and restart before crash

show task memory detail | match so_in

Disable jflow if not needed

all

Remove jflow configuration to eliminate the trigger condition

delete forwarding-options sampling
delete forwarding-options port-mirroring

🧯 If You Can't Patch

  • Implement aggressive monitoring of rpd memory usage with automated alerts
  • Establish procedures for rapid rpd restart when memory thresholds are exceeded

🔍 How to Verify

Check if Vulnerable:

Check version with 'show version' and compare against affected versions. Monitor memory with 'show task memory detail | match so_in' for increasing values.

Check Version:

show version

Verify Fix Applied:

Confirm version is patched with 'show version'. Monitor memory usage over time to ensure stable values.

📡 Detection & Monitoring

Log Indicators:

  • rpd crash logs
  • memory allocation failure messages
  • high memory usage warnings

Network Indicators:

  • BGP session instability
  • routing table inconsistencies
  • increased rpd restart frequency

SIEM Query:

source="junos" AND ("rpd" AND ("crash" OR "restart" OR "memory"))

🔗 References

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