CVE-2023-36841

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

The product does not properly control the allocation and maintenance of a limited resource.

Affected Software

Potential Mitigations

• Mitigation of resource exhaustion attacks requires that the target system either:

• The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.

• The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/147.html
• https://cwe.mitre.org/data/definitions/227.html
• https://cwe.mitre.org/data/definitions/492.html

References

• https://supportportal.juniper.net/JSA73172
• https://supportportal.juniper.net/JSA73172