CVE-2025-52947 Junos OS: ACX Series: When 'hot-standby' mode is configured for an L2 circuit, interface flap causes the FEB to crash
Attackers can crash the Forwarding Engine Board on Juniper ACX routers by flapping interfaces when hot-standby mode is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-52947?
CVE-2025-52947 is a high-severity denial of service vulnerability in Juniper Junos, published on 11 Jul 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
An Improper Handling of Exceptional Conditions vulnerability in route processing of Juniper Networks Junos OS on specific end-of-life (EOL) ACX Series platforms allows an attacker to crash the Forwarding Engine Board (FEB) by flapping an interface, leading to a Denial of Service (DoS).
On ACX1000, ACX1100, ACX2000, ACX2100, ACX2200, ACX4000, ACX5048, and ACX5096 devices, FEB0 will crash when the primary path port of the L2 circuit IGP (Interior Gateway Protocol) on the local device goes down. This issue is seen only when 'hot-standby' mode is configured for the L2 circuit.
This issue affects Junos OS on ACX1000, ACX1100, ACX2000, ACX2100, ACX2200, ACX4000, ACX5048, and ACX5096:
* all versions before 21.2R3-S9.
Weakness: CWE-755
Which versions are affected by CVE-2025-52947?
It affects 1 product.
Products include Juniper Junos.
How do I fix CVE-2025-52947?
No fix has been published for CVE-2025-52947 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-2025-52947 being exploited?
There is no known exploitation of CVE-2025-52947 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-xw3x-vr3j-962f.