CVE-2024-21600

Name: CVE-2024-21600
Creator: NVD / NIST
Published: 2024-01-12T01:15:47.857+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 0.32%

Last modified Jun 17, 2026

CVE-2024-21600 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. An Improper Neutralization of Equivalent Special Elements vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on PTX Series allows a unauthenticated, adjacent attacker to cause a Denial of Service (DoS). When MPLS packets are meant to be sent to a flexible tunnel interface (FTI) and if the FTI tunnel is down, these will hit the reject NH, due to which the packets get sent to the CPU and cause a host path wedge condition. This will cause the FPC to hang and requires a manual restart to recover. Please note that this issue specifically affects PTX1000, PTX3000, PTX5000 with FPC3, PTX10002-60C, and PTX10008/16 with LC110x. EPSS estimates a 0.32% chance of exploitation in the next 30 days.

Description

An Improper Neutralization of Equivalent Special Elements vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on PTX Series allows a unauthenticated, adjacent attacker to cause a Denial of Service (DoS). When MPLS packets are meant to be sent to a flexible tunnel interface (FTI) and if the FTI tunnel is down, these will hit the reject NH, due to which the packets get sent to the CPU and cause a host path wedge condition. This will cause the FPC to hang and requires a manual restart to recover. Please note that this issue specifically affects PTX1000, PTX3000, PTX5000 with FPC3, PTX10002-60C, and PTX10008/16 with LC110x. Other PTX Series devices and Line Cards (LC) are not affected. The following log message can be seen when the issue occurs: Cmerror Op Set: Host Loopback: HOST LOOPBACK WEDGE DETECTED IN PATH ID <id> (URI: /fpc/<fpc>/pfe/<pfe>/cm/<cm>/Host_Loopback/<cm>/HOST_LOOPBACK_MAKE_CMERROR_ID[<id>]) This issue affects Juniper Networks Junos OS: * All versions earlier than 20.4R3-S8; * 21.1 versions earlier than 21.1R3-S4; * 21.2 versions earlier than 21.2R3-S6; * 21.3 versions earlier than 21.3R3-S3; * 21.4 versions earlier than 21.4R3-S5; * 22.1 versions earlier than 22.1R2-S2, 22.1R3; * 22.2 versions earlier than 22.2R2-S1, 22.2R3.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.32%

24.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-76

Affected Software

Vendor	Product	Versions
Juniper	Junos	20.4
Juniper	Junos	21.1
Juniper	Junos	21.2
Juniper	Junos	21.3
Juniper	Junos	21.4
Juniper	Junos	22.1
Juniper	Junos	22.2

References

https://supportportal.juniper.net/JSA75741Vendor Advisory
https://www.first.org/cvss/calculator/4.0#CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:LThird Party Advisory
https://supportportal.juniper.net/JSA75741Vendor Advisory
https://www.first.org/cvss/calculator/4.0#CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:LThird Party Advisory

Timeline

Published: Jan 12, 2024
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2024-21600?

How severe is CVE-2024-21600?

CVE-2024-21600 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.32% probability of exploitation in the next 30 days.

How do I fix CVE-2024-21600?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2024-21600?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST