CVE-2023-36841 Junos OS: MX Series: Receipt of malformed TCP traffic will cause a Denial of Service
Unauthenticated attackers can cause a denial of service on Juniper MX routers by sending malformed TCP traffic to interfaces configured with PPPoE and tcp-mss.
- 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-2023-36841?
CVE-2023-36841 is a high-severity denial of service vulnerability in Juniper Junos, published on 12 Oct 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows a unauthenticated network-based attacker to cause an infinite loop, resulting in a Denial of Service (DoS).
An attacker who sends malformed TCP traffic via an interface configured with PPPoE, causes an infinite loop on the respective PFE. This results in consuming all resources and a manual restart is needed to recover.
This issue affects interfaces with PPPoE configured and tcp-mss enabled.
This issue affects Juniper Networks Junos OS
* All versions prior to 20.4R3-S7; * 21.1 version 21.1R1 and later versions; * 21.2 versions prior to 21.2R3-S6; * 21.3 versions prior to 21.3R3-S5; * 21.4 versions prior to 21.4R3-S3; * 22.1 versions prior to 22.1R3-S4; * 22.2 versions prior to 22.2R3; * 22.3 versions prior to 22.3R2-S2; * 22.4 versions prior to 22.4R2;
Weakness: CWE-400
Which versions are affected by CVE-2023-36841?
It affects 1 product.
Products include Juniper Junos.
How do I fix CVE-2023-36841?
No fix has been published for CVE-2023-36841 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-2023-36841 being exploited?
There is no known exploitation of CVE-2023-36841 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-j5xw-gh42-g53c.