CVE-2024-39542 Junos OS and Junos OS Evolved: A malformed CFM packet or specific transit traffic leads to FPC crash
An unauthenticated attacker can crash the Packet Forwarding Engine via malformed CFM packets or specific transit traffic, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2024-39542?
CVE-2024-39542 is a high-severity denial of service vulnerability in Juniper Junos, published on 11 Jul 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
An Improper Validation of Syntactic Correctness of Input vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on MX Series with MPC10/11 or LC9600, MX304, and Junos OS Evolved on ACX Series and PTX Series allows an unauthenticated, network based attacker to cause a Denial-of-Service (DoS).
This issue can occur in two scenarios:
1. If a device, which is configured with SFLOW and ECMP, receives specific valid transit traffic, which is subject to sampling, the packetio process crashes, which in turn leads to an evo-aftman crash and causes the FPC to stop working until it is restarted. (This scenario is only applicable to PTX but not to ACX or MX.)
2. If a device receives a malformed CFM packet on an interface configured with CFM, the packetio process crashes, which in turn leads to an evo-aftman crash and causes the FPC to stop working until it is restarted. Please note that the CVSS score is for the formally more severe issue 1.
The CVSS score for scenario 2. is: 6.5 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
This issue affects Junos OS:
* All versions before 21.2R3-S4, * 21.4 versions before 21.4R2, * 22.2 versions before 22.2R3-S2;
Junos OS Evolved:
* All versions before 21.2R3-S8-EVO, * 21.4 versions before 21.4R2-EVO.
Weakness: CWE-1286
Which versions are affected by CVE-2024-39542?
It affects 2 products.
Products include Juniper Junos, Juniper Junos Os Evolved.
How do I fix CVE-2024-39542?
No fix has been published for CVE-2024-39542 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2024-39542 being exploited?
There is no known exploitation of CVE-2024-39542 in the wild and no public exploit code.
Other vulnerabilities in Juniper Junos
- CVE-2023-36845 Juniper Junos OS EX Series and SRX Series PHP External Variable Modification
- CVE-2020-1631 Juniper Junos OS Path Traversal
- CVE-2025-21590 Juniper Junos OS Improper Isolation or Compartmentalization
- CVE-2023-36851 Juniper Junos OS SRX Series Missing Authentication for Critical Function
- CVE-2023-36844 Juniper Junos OS EX Series PHP External Variable Modification
Sources
Also known as GHSA-34f4-m9rh-9x9j.